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Magnetochemistry, Volume 9, Issue 5 (May 2023) – 26 articles

Cover Story (view full-size image): Graphene's exceptional properties and atom-thick structure have drawn significant attention, particularly for their potential in low-dimensional magnetic tunnel junctions. This research explores the topological characteristics of graphene in magnetic Ni/hBN-Gr-hBN/Ni junctions. By utilizing the magnetic proximity effect, a spin-topological electronic valve was achieved in graphene's in-plane conductance with three memory states, which are not typically observed in standard magnetic junctions. These findings advance our understanding of graphene's interaction with magnets and pave the way for enhanced functionality in spintronics and information storage applications. View this paper
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10 pages, 2107 KiB  
Article
Magnetic Dilution as a Direct Method for Detecting and Evaluation of Exchange Interactions between Rare Earth Elements in Oxide Systems
by Natalia Chezhina and Anna Fedorova
Magnetochemistry 2023, 9(5), 137; https://doi.org/10.3390/magnetochemistry9050137 - 20 May 2023
Viewed by 1025
Abstract
This work is devoted to the study of exchange interactions between rare earth atoms in the LaAlO3 matrix. Using the magnetic dilution method, the study of concentration and temperature dependences of magnetic susceptibility and effective magnetic moments of diluted solid solutions the [...] Read more.
This work is devoted to the study of exchange interactions between rare earth atoms in the LaAlO3 matrix. Using the magnetic dilution method, the study of concentration and temperature dependences of magnetic susceptibility and effective magnetic moments of diluted solid solutions the magnetic characteristics of single rare earth atoms and the character of superexchange between them are described—antiferromagnetic at low concentrations, and for samarium, predominantly ferromagnetic within greater clusters as the concentration increases. The development of superexchange is similar to the exchange between d-elements in the same matrix. Full article
(This article belongs to the Special Issue Phase Change Material and Magnetic Research)
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14 pages, 8507 KiB  
Article
Magnetic Adsorbent Based on Faujasite Zeolite Decorated with Magnesium Ferrite Nanoparticles for Metal Ion Removal
by Mariana Rodrigues Meirelles, João Otávio Donizette Malafatti, Márcia Tsuyama Escote, Alexandre Henrique Pinto and Elaine Cristina Paris
Magnetochemistry 2023, 9(5), 136; https://doi.org/10.3390/magnetochemistry9050136 - 20 May 2023
Cited by 2 | Viewed by 1262
Abstract
Magnetic nanoparticles are a promising alternative as a support in adsorption processes, aiming at the easy recovery of the aqueous medium. A faujasite zeolite (FAU) surface was decorated with magnesium ferrite (MgFe2O4) nanoparticles. FAU is a porous adsorbent with [...] Read more.
Magnetic nanoparticles are a promising alternative as a support in adsorption processes, aiming at the easy recovery of the aqueous medium. A faujasite zeolite (FAU) surface was decorated with magnesium ferrite (MgFe2O4) nanoparticles. FAU is a porous adsorbent with high specific surface area (SSA) and chemical stability. The FAU:MgFe2O4 nanocomposite 3:1 ratio (w w−1) promotes the combination of the surface and magnetic properties. The results showed the effectiveness of the MgFe2O4 immobilization on the FAU surface, exhibiting a high SSA of 400 m2 g−1. The saturation magnetization (Ms) was verified as 5.9 emu g−1 for MgFe2O4 and 0.47 emu g−1 for FAU:MgFe2O4, an environmentally friendly system with soft magnetic characteristics. The magnetic nanocomposite achieved high adsorption values of around 94% removal for Co2+ and Mn2+ ions. Regarding its reuse, the nanocomposite preserved adsorption activity of above 65% until the third cycle. Thus, the FAU:MgFe2O4 nanocomposite presented favorable adsorptive, magnetic, and recovery properties for reuse cycles in polluted water. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: State of the Art and Future Perspectives)
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9 pages, 1997 KiB  
Communication
Superconducting Gap Structure of the Noncentrosymmetric Topological Superconductor Candidate HfRuP
by Debarchan Das, Devashibhai Adroja, Rajesh Tripathi, Zurab Guguchia, Fabian Hotz, Hubertus Luetkens, Zhijun Wang, Dayu Yan, Huiqian Luo and Youguo Shi
Magnetochemistry 2023, 9(5), 135; https://doi.org/10.3390/magnetochemistry9050135 - 19 May 2023
Viewed by 1175
Abstract
We investigate the gap symmetry of the topological superconductor candidate HfRuP, which crystallizes in a noncentrosymmetric hexagonal crystal structure, using muon spin rotation/relaxation (μSR) measurements in transverse-field (TF) geometry. The temperature and magnetic field dependencies of the superconducting relaxation rate derived [...] Read more.
We investigate the gap symmetry of the topological superconductor candidate HfRuP, which crystallizes in a noncentrosymmetric hexagonal crystal structure, using muon spin rotation/relaxation (μSR) measurements in transverse-field (TF) geometry. The temperature and magnetic field dependencies of the superconducting relaxation rate derived from the TF-μSR spectra can be well described by an isotropic s-wave gap. The superconducting carrier density ns = 1.41(1) × 1026 m3 and the magnetic penetration depth, λ(0) = 603(2) nm, were calculated from the TF-μSR data. Interestingly, the ratio between the superconducting transition temperature and the superfluid density, Tc/λ2(0) ∼ 3.3, is very close to those of unconventional superconductors. Further, our zero-field (ZF) μSR results do not show any considerable change in the muon spin relaxation above and below the superconducting transition temperature, suggesting that time-reversal symmetry is preserved in the superconducting state of this superconductor. Full article
(This article belongs to the Section Applications of Magnetism and Magnetic Materials)
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14 pages, 6095 KiB  
Article
Influence of High Viscosity and Magnetoviscous Effect on the Washout Resistance of Magnetic Fluid
by Zixian Li, Decai Li, Yanwen Li and Shuntao Han
Magnetochemistry 2023, 9(5), 134; https://doi.org/10.3390/magnetochemistry9050134 - 19 May 2023
Viewed by 1119
Abstract
Magnetic fluid seals have long been thought to be a successful sealing form while sealing liquids are always a challenge. The instability of the liquid–liquid interface under the washout has become the key technical problem that hinders the realization of sealing liquid. This [...] Read more.
Magnetic fluid seals have long been thought to be a successful sealing form while sealing liquids are always a challenge. The instability of the liquid–liquid interface under the washout has become the key technical problem that hinders the realization of sealing liquid. This work mainly presents an experimental study about the influence of high viscosity and magnetoviscous effects on washout resistance. Three engine oil-based magnetic fluids of different viscosities were prepared with two kinds of surfactants. The magnetoviscous effects of the prepared magnetic fluids under different working conditions were found through rheological experiments. The viscosity of the three samples decreased at most by about 100 times with the shear rate increasing. An experimental platform was designed and built for the washout tests. The entire process of magnetic fluids being washed away was obtained experimentally. The magnetic fluid of higher viscosity can remain stationary with lower magnetic force. The quantitative results show that the viscosity of the magnetic fluid has a significant influence on washout resistance under a magnetic field. Full article
(This article belongs to the Special Issue Advanced Applications of Magnetic Field-Responsive Fluid)
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6 pages, 226 KiB  
Editorial
Magnetic Materials, Thin Films and Nanostructures
by Catalin-Daniel Constantinescu and Lucian-Gabriel Petrescu
Magnetochemistry 2023, 9(5), 133; https://doi.org/10.3390/magnetochemistry9050133 - 19 May 2023
Viewed by 1894
Abstract
In this first volume, we cover relevant aspects of chemical and physical processes of the production and characterization of magnetic materials in bulk, thin films, nanostructures, and/or nanocomposites, as well as modeling aspects involving such structures. Accordingly, this volume presents eleven original research [...] Read more.
In this first volume, we cover relevant aspects of chemical and physical processes of the production and characterization of magnetic materials in bulk, thin films, nanostructures, and/or nanocomposites, as well as modeling aspects involving such structures. Accordingly, this volume presents eleven original research and review works on the challenges and trends covering fundamental and experimental work, with a special focus on the design, synthesis, and characterization of various types of magnetic materials, and the study of their structure–property relationships. State-of-the-art results on the development of new experimental concepts, leading to the transfer, chemical transformation, and high-resolution patterning of advanced thin films and nanomaterials, and to the design and fabrication of devices, are also presented and discussed. Full article
(This article belongs to the Special Issue Magnetic Materials, Thin Films and Nanostructures)
15 pages, 3887 KiB  
Article
Solid Phase Extraction Penicillin and Tetracycline in Human Serum Using Magnetic Graphene Oxide-Based Sulfide Nanocomposite
by Hassan Sereshti, Sara Soltani, Nanthini Sridewi, Elham Salehi, Ehsan Parandi, Hamid Rashid Nodeh and Syed Shahabuddin
Magnetochemistry 2023, 9(5), 132; https://doi.org/10.3390/magnetochemistry9050132 - 19 May 2023
Cited by 5 | Viewed by 1356
Abstract
Herein, we report a procedure for separating and preconcentrating antibiotics from human serum using a novel adsorbent of magnetic graphene oxide (MGO) and cadmium sulfide (CdS) nanoparticles. The adsorbent (MGO@CdS) was characterized using Fourier transformed infrared spectrometry (FT-IR), energy dispersive X-ray spectroscopy (EDX), [...] Read more.
Herein, we report a procedure for separating and preconcentrating antibiotics from human serum using a novel adsorbent of magnetic graphene oxide (MGO) and cadmium sulfide (CdS) nanoparticles. The adsorbent (MGO@CdS) was characterized using Fourier transformed infrared spectrometry (FT-IR), energy dispersive X-ray spectroscopy (EDX), and field emission scanning electron microscopy (FE-SEM). The effective parameters for extraction efficiency were investigated, including the desorption solvent’s nature, pH, adsorbent dose, salt concentration, extraction time, and volume of sample solution and desorption solvent. The proposed procedure proved to be fast (20 min), simple (two stages), and cost-effective (20 mg of nanoparticles). Under the optimum conditions, satisfactory linearity (R2 > 0.992) was obtained, and limits of detection (LOD) were estimated as 4.5 µg L−1 (for tetracycline) and 5.7 µg L−1 (for penicillin) and a linear dynamic range (LDR) from 20 to 200 µg L−1. The magnetic solid phase extraction (MSPE) method based on MGO@CdS has achieved a satisfactory recovery (71.5–109.5%) in human serum for the selected antibiotics. Finally, the antibiotic’s release was studied in simulated fluids of the gastric (pH = 1.2) and intestine (pH = 7.4). In this light, we demonstrate that the newly introduced adsorbent can be used in drug extraction from different biological media. Full article
(This article belongs to the Special Issue Application of Magnetic Materials in Environmental Remediation)
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14 pages, 2891 KiB  
Article
Slow Magnetic Relaxation and Luminescence Properties in Tetra β-Diketonate Lanthanide(III) Complexes
by Saskia Speed, Ànnia Tubau, Ramon Vicente, Eva Castro and Mercè Font-Bardia
Magnetochemistry 2023, 9(5), 131; https://doi.org/10.3390/magnetochemistry9050131 - 16 May 2023
Cited by 1 | Viewed by 1010
Abstract
The reaction of [Ln(btfa)3(H2O)2] (btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate) with additional 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbtfa) and acridine (Acr) in ethanol allows the isolation of the mononuclear compounds HAcr[Nd(btfa)4]·EtOH, (1) and HAcr[Ln(btfa)4], Ln = Dy [...] Read more.
The reaction of [Ln(btfa)3(H2O)2] (btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate) with additional 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbtfa) and acridine (Acr) in ethanol allows the isolation of the mononuclear compounds HAcr[Nd(btfa)4]·EtOH, (1) and HAcr[Ln(btfa)4], Ln = Dy (2) and Yb (3); HAcr+ = acridinium cation. Magnetic measurements indicate that complexes 13 show field-induced single-ion magnet behavior with anisotropy energy barriers and preexponential factors of Ueff = 20.7 cm−1, τ0 = 24.5 × 10−8 s; Ueff = 40.5 cm−1, τ0 = 8.6 × 10−10 s and Ueff = 22.7 cm−1, τ0 = 8.4 × 10−8 s, for 13 respectively. The solid-state luminescence emission in the NIR region shows efficient energy transfer from the 4,4,4-trifluoro-1-phenyl-1,3-butanedionate ligands to the central Ln3+ ion in the case of compounds 1 and 3. Full article
(This article belongs to the Special Issue Magnetic Relaxation in Metal Complexes)
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15 pages, 2237 KiB  
Article
A Chain of Vertex-Sharing {CoIII2CoII2}n Squares with Single-Ion Magnet Behavior
by Maria-Gabriela Alexandru, Diana Visinescu, Sergiu Shova, Joan Cano, Nicolás Moliner, Francesc Lloret and Miguel Julve
Magnetochemistry 2023, 9(5), 130; https://doi.org/10.3390/magnetochemistry9050130 - 15 May 2023
Viewed by 1176
Abstract
A new mixed-valence one-dimensional coordination polymer of formula {[CoII(MeOH)2][(μ-NC)2CoIII(dmphen)(CN)2]2}n·2nH2O (1) was obtained by reacting the Ph4P[CoII(dmphen)(CN)3 [...] Read more.
A new mixed-valence one-dimensional coordination polymer of formula {[CoII(MeOH)2][(μ-NC)2CoIII(dmphen)(CN)2]2}n·2nH2O (1) was obtained by reacting the Ph4P[CoII(dmphen)(CN)3] metalloligand (dmphen = 2,9-dimethyl-1,10-phenanthroline and Ph4P+ = tetraphenylphosphonium ion) with cobalt(II) acetate tetrahydrate. The structural analysis shows the formation of a neutral 4,2-ribbon-like chain of vertex-sharing cyanido-bridged {CoIII2CoII2} squares in which the metalloligand underwent an oxidation process and a reorganization to form {CoIII(dmphen)(CN)4} linkers that coordinate to the [CoII(MeOH)2]2+ units through single cyanido ligands. Both cobalt(II) and Co(III) cations are six-coordinated in distorted octahedral environments. The shortest intrachain distance between the paramagnetic cobalt(II) ions is 7.36 Å, a value which is shorter than the shortest interchain one (10.36 Å). Variable-temperature (1.9–300 K) static (dc) magnetic measurements for 1 indicate the occurrence of magnetically isolated high-spin cobalt(II) ions with a D value of +67.0 cm−1. Dynamic alternating current (ac) magnetic measurements between 2.0–13 K reveal that 1 exhibits slow magnetic relaxation under non-zero applied dc fields, being thus a new example of field-induced SIM with easy-plane magnetic anisotropy. Theoretical calculations by CASSCF/NEVPT2 on 1 support the results from magnetometry. The relaxation of the magnetization occurs in the ground state under external dc fields through a two-phonon Raman process and one intra-Kramers mechanism. Full article
(This article belongs to the Special Issue Advances in Molecular Magnetism)
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13 pages, 3732 KiB  
Article
Novel Concentric Magnetic Continuum Robot with Multiple Stiffness Modes for Potential Delivery of Nanomedicine
by Na Li, Daojing Lin, Junfeng Wu, Quan Gan, Xingyue Hu and Niandong Jiao
Magnetochemistry 2023, 9(5), 129; https://doi.org/10.3390/magnetochemistry9050129 - 12 May 2023
Cited by 1 | Viewed by 1647
Abstract
The utilisation of miniature robots has become essential in the domain of minimally invasive surgery and long-distance delivery of nanomedicine. Among these, the miniature magnetic continuum robot (MCR) stands out because of its simple structure and dexterity, which allow it to penetrate small [...] Read more.
The utilisation of miniature robots has become essential in the domain of minimally invasive surgery and long-distance delivery of nanomedicine. Among these, the miniature magnetic continuum robot (MCR) stands out because of its simple structure and dexterity, which allow it to penetrate small cavities, transport specialised tools such as a laser, and deliver medications to support surgical treatment. Nevertheless, because of their soft bodies with a single stiffness, conventional MCRs have limited controllability when navigating through intricate cavities. To address this limitation, we propose a novel concentric magnetic continuum robot (C-MCR) comprising a concentric magnetic catheter with a guidewire having varying stiffness. The C-MCR allows substantial curvature bending owing to its difference in stiffness, and its detachable nature allows it to have four working modes to adapt to specific application requirements with improved stiffness controllability. Experiments demonstrate the ability of the C-MCR to navigate complex pathways and deliver nanomedicines over long distances to specific areas via its internal channels using a large homemade eight-coil electromagnetic system. The C-MCR offers promising application prospects for the long-distance delivery of tailored nanomedicines because of its simple operation, reduced risks, and larger attainable workspace. Full article
(This article belongs to the Section Magnetic Materials)
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15 pages, 4019 KiB  
Article
Transformation Pathways of Ferromagnetic Mn-Al-Ga-Ni
by Shane Palmer, John Martin, Paul Lindquist and Peter Müllner
Magnetochemistry 2023, 9(5), 128; https://doi.org/10.3390/magnetochemistry9050128 - 11 May 2023
Cited by 1 | Viewed by 923
Abstract
This study investigates the impact of alloying Mn-Al-Ga with 3 at.-% Ni and the stability and formation mechanisms of the τ phase and the resulting magnetic properties. The stabilizing effect of Ga on the τ phase was verified, and the ternary alloy’s magnetization [...] Read more.
This study investigates the impact of alloying Mn-Al-Ga with 3 at.-% Ni and the stability and formation mechanisms of the τ phase and the resulting magnetic properties. The stabilizing effect of Ga on the τ phase was verified, and the ternary alloy’s magnetization was measured up to M2T=482kA m1. The phase transformation from γ2 to τ in ternary Mn-Al-Ga was demonstrated microscopically. The solubility limit of Ni into the τ phase was exceeded at 3 at.-% and a primitive cubic κ phase formed. The Ni addition stabilized the τ phase. The highest magnetization at 2 T for the Mn52Al39.4Ga5.6Ni3 alloy was M2T=416 kA m1. A new transformation pathway was demonstrated by first annealing the Mn-Al-Ga-Ni alloy at 800 °C for 24 h, which forms a nearly single κ phase, which is followed by a second anneal at 500 °C for 24 h at which the τ phase formed with some remaining κ phase. This is a new transformation mechanism since it involves a phase reaction from κ to τ. The energy product of the Mn-Al-Ga-Ni alloy exceeded that of the ternary Mn-Al-Ga alloy by a factor of 4.5. The κ-phase particles in the Mn-Al-Ga-Ni alloy hinder magnetic domain boundary motion, thus providing a method for magnetic hardening and increasing the energy product. Full article
(This article belongs to the Special Issue Soft and Hard Magnetic Materials: Latest Advances and Prospects)
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36 pages, 6819 KiB  
Review
Nanocomposites of Ferrites with TiO2, SiO2 and Carbon Quantum Dots as Photocatalysts for Degradation of Organic Pollutants and Microbes
by Ajaypal Kaur, Manpreet Kaur, Vasundhara Singh and Pratibha Vyas
Magnetochemistry 2023, 9(5), 127; https://doi.org/10.3390/magnetochemistry9050127 - 09 May 2023
Cited by 4 | Viewed by 2571
Abstract
Ferrites are important magnetic materials used in electronic devices. Nanocomposites of ferrites with TiO2, SiO2 and carbon quantum dots have gained recent interest due to their unique advantages, such as high chemical stability, surface-active sites, high specific surface area, non-toxicity, [...] Read more.
Ferrites are important magnetic materials used in electronic devices. Nanocomposites of ferrites with TiO2, SiO2 and carbon quantum dots have gained recent interest due to their unique advantages, such as high chemical stability, surface-active sites, high specific surface area, non-toxicity, excellent optical properties, and tunable porosity. In the present review, general and adaptable coprecipitation, sol–gel, hydrothermal, solvothermal, and Stöber methods for the fabrication of nanocomposites are discussed. These materials offer the advantage of magnetic recovery and superior photocatalytic performance. The potential of nanocomposites to act as photocatalysts to eliminate organic pollutants and microbes from water is discussed. Mechanisms involved in these applications are also elaborated upon. The review provides a detailed study of recent applications and future perspectives of nanocomposites in sustainable water treatment. Full article
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12 pages, 2980 KiB  
Article
Effect of SiO2/Organosilicone Double Insulation Coating Processes on the Properties of Ferrosilicon Magnetic Cores
by Shaochuan Lin, Zihan Zhou, Jinghan Jin, Xueyan Hu, Shaogang Li and Nachaun Ju
Magnetochemistry 2023, 9(5), 126; https://doi.org/10.3390/magnetochemistry9050126 - 09 May 2023
Cited by 1 | Viewed by 1217
Abstract
A nano-SiO2 inorganic insulation layer was coated on the surface of FeSi magnetic powder via in situ fluidised vapour deposition. The surface was then coated with organosilicon resin to form an inorganic/organic double-insulating layer. Post-forming and annealing, a ferrosilicon magnetic powder core [...] Read more.
A nano-SiO2 inorganic insulation layer was coated on the surface of FeSi magnetic powder via in situ fluidised vapour deposition. The surface was then coated with organosilicon resin to form an inorganic/organic double-insulating layer. Post-forming and annealing, a ferrosilicon magnetic powder core was prepared. The effects of organosilicon resin content and pressing pressure on the permeability and loss of the ferrosilicon magnetic core were studied. When the ferrosilicon magnetic core was doubly insulated with SiO2/silicone resin, the silicone resin content increased, the insulation coating gradually thickens, and the saturation magnetic-induction intensity of the magnet gradually decreases; the density and effective permeability showed a trend of increasing first and then decreasing. Increasing the forming pressure can reduce the loss of the core, thereby improving the performance of the core and increasing the permeability without damaging the double-cladding layer. In the powder with the optimised silicone resin content (1.5 wt.%), the magnetic properties of the magnetic core were maximised after preparation at 1500 MPa followed by heat treatment at 773 K. The saturation magnetisation was 187.5 emu/g and the resistivity and permeability reached 10.5 Ω·cm and 49.6, respectively, at 100 mT and 50 kHz. The total loss was 905 mW/cm3. Full article
(This article belongs to the Special Issue Advances in Soft Magnetic Materials)
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8 pages, 2139 KiB  
Communication
In Situ Tuning of Magnetism in Fe3GeTe2 via Argon Ions Irradiation
by Shan Wang, Chuanwu Cao and Jian-Hao Chen
Magnetochemistry 2023, 9(5), 125; https://doi.org/10.3390/magnetochemistry9050125 - 09 May 2023
Viewed by 1224
Abstract
We report the continuous argon ions irradiation of itinerant Fe3GeTe2, a two-dimensional ferromagnetic metal, with the modification to its transport properties measured in situ. Our results show that defects generated by argon ions irradiation can significantly weaken the [...] Read more.
We report the continuous argon ions irradiation of itinerant Fe3GeTe2, a two-dimensional ferromagnetic metal, with the modification to its transport properties measured in situ. Our results show that defects generated by argon ions irradiation can significantly weaken the magnetization (M) and coercive field (Hc) of Fe3GeTe2, demonstrating the tunable magnetism of this material. Specifically, at base temperature, we observed a reduction of M and Hc by up to 40% and 62.4%, respectively. After separating the contribution from different mechanisms based on the Tian-Ye-Jin (TYJ) scaling relation, it’s the skew scattering that dominates the contribution to anomalous Hall effect in argon ions irradiated Fe3GeTe2. These findings highlight the potential of in situ transport modification as an effective method for tailoring the magnetic properties of two-dimensional magnetic materials, and provides new insights into the mechanisms underlying the tunable magnetism in Fe3GeTe2. Full article
(This article belongs to the Special Issue Advances in Magnetic Two Dimensional Materials)
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12 pages, 2140 KiB  
Article
Quantitative Evaluation of the Lymph Node Metastases in the Head and Neck Malignancies Using Diffusion-Weighted Imaging and Apparent Diffusion Coefficient Mapping: A Bicentric Study
by Maria Paola Belfiore, Luigi Gallo, Alfonso Reginelli, Pasquale Maria Parrella, Gaetano Maria Russo, Valentina Caliendo, Morena Fasano, Giovanni Ciani, Raffaele Zeccolini, Carlo Liguori, Valerio Nardone and Salvatore Cappabianca
Magnetochemistry 2023, 9(5), 124; https://doi.org/10.3390/magnetochemistry9050124 - 08 May 2023
Cited by 1 | Viewed by 1360
Abstract
This study aimed to determine if diffusion-weighted imaging (DWI) can differentiate between benign and malignant lymph nodes in patients with head and neck cancer. A total of 55 patients with confirmed head and neck cancer and enlarged neck nodes were enrolled and evaluated [...] Read more.
This study aimed to determine if diffusion-weighted imaging (DWI) can differentiate between benign and malignant lymph nodes in patients with head and neck cancer. A total of 55 patients with confirmed head and neck cancer and enlarged neck nodes were enrolled and evaluated by two radiologists using a workstation. Lymph nodes were analyzed using 3D regions of interest (ROIs) placed on T2-weighted images and compared to the corresponding DWI images. This study found that DWI and ADC values can be used to assess metastatic lymph nodes in the neck and that the sensitivity, specificity, and AUC of a narrower ROI for recognizing metastases were greater compared to the ADC value of the whole node. The study also found that the size of the ROI affects ADC values. The results suggest that DWI can accurately predict the status of cervical lymph nodes in patients with head and neck cancer and that it may be useful in diagnosing, determining the stage, developing a treatment plan, and monitoring these patients. Full article
(This article belongs to the Special Issue Advanced Applications of Magnetic Resonance)
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13 pages, 3142 KiB  
Article
Effect of an External Magnetic Field on the Hydrogen Reduction of Magnetite Nanoparticles in a Polymer Matrix
by Petr Chernavskii, Sveta Ozkan, Galina Karpacheva, Galina Pankina and Nikolai Perov
Magnetochemistry 2023, 9(5), 123; https://doi.org/10.3390/magnetochemistry9050123 - 07 May 2023
Viewed by 1050
Abstract
A hybrid electromagnetic nanomaterial, which is a matrix based on a conjugated polymer of poly-3-amine-7-methylamine-2-methylphenazine with dispersed magnetite nanoparticles immobilized on multi-walled carbon nanotubes, has been synthesized. In situ magnetometry was used to study the kinetics of the hydrogen reduction of Fe3 [...] Read more.
A hybrid electromagnetic nanomaterial, which is a matrix based on a conjugated polymer of poly-3-amine-7-methylamine-2-methylphenazine with dispersed magnetite nanoparticles immobilized on multi-walled carbon nanotubes, has been synthesized. In situ magnetometry was used to study the kinetics of the hydrogen reduction of Fe3O4 immobilized in the structure of a ternary nanocomposite in magnetic fields of different intensities. An increase in the magnetite reduction reaction rate with the formation of metallic iron nanoparticles at T=420C and at a magnetic field strength in the range of 60–3000 Oe was observed. The dependence of the degree of conversion of Fe3O4 on the magnetic field strength was established. Full article
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10 pages, 2081 KiB  
Article
A Cu12 Metallacycle Assembled from Four C3-Symmetric Spin Frustrated Triangular Units
by Basharat Ali, Grégoire David, Frédéric Gendron, Xiao-Lei Li, Olivier Cador, Winfried Plass, Boris Le Guennic and Jinkui Tang
Magnetochemistry 2023, 9(5), 122; https://doi.org/10.3390/magnetochemistry9050122 - 06 May 2023
Viewed by 1281
Abstract
Assembling metallacycles with interesting topological arrangements is a critical task for chemists. We report here a novel dodecanuclear CuII compound, [{Cu3L(µ-N3)}4(Py)14]·2Py (Cu12) (where Py = pyridine and [H6L]Cl = [...] Read more.
Assembling metallacycles with interesting topological arrangements is a critical task for chemists. We report here a novel dodecanuclear CuII compound, [{Cu3L(µ-N3)}4(Py)14]·2Py (Cu12) (where Py = pyridine and [H6L]Cl = tris(2-hydroxybenzylidine)triaminoguanidinium chloride, respectively), with the topology of a cycle accomplished by four two-connecting approximately flat C3-symmetric guanidine-based ligands. Each ligand affords three tridentate metal-binding cavities and the four node-to-node connections through single azido bridges are provided by pairs of metal centers. A theoretical investigation using CASSCF in addition to DFT calculations showed strong antiferromagnetic coupling within the Cu3-triangles, resulting in spin-frustrated systems. However, these calculations were not able to properly reproduce the very weak antiferromagnetic couplings between the triangle units, highlighting the challenge of describing the magnetic behavior of this compound. Full article
(This article belongs to the Special Issue Advances in Molecular Magnetism)
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13 pages, 3645 KiB  
Article
Unusual Compositions of Fe-Nb Alloy Precipitates in Iron-Implanted LiNbO3
by Almaz L. Zinnatullin, Andrei V. Petrov, Roman V. Yusupov, Valerii F. Valeev, Rustam I. Khaibullin and Farit G. Vagizov
Magnetochemistry 2023, 9(5), 121; https://doi.org/10.3390/magnetochemistry9050121 - 06 May 2023
Viewed by 998
Abstract
The results of a study of heavy implantation of a LiNbO3 crystal with iron ions are reported for the first time. The X-cut LiNbO3 substrate was implanted with 40-keV Fe+ ions to the fluence of 1.5·1017 ions/cm2. [...] Read more.
The results of a study of heavy implantation of a LiNbO3 crystal with iron ions are reported for the first time. The X-cut LiNbO3 substrate was implanted with 40-keV Fe+ ions to the fluence of 1.5·1017 ions/cm2. The sample reveals pronounced ferromagnetic properties at room temperature. However, the ferromagnetic response observed in the iron-implanted LiNbO3 differs from the magnetic behavior of other oxides implanted with iron ions under the same conditions. This difference occurs from the unusual magnetic phase composition of the implanted surface layer of the LiNbO3 in which the iron implant precipitates in the form of the nanoscale alloy of metallic iron with niobium. Based on Mössbauer spectroscopy data, we estimated the Nb content in the ion-synthesized nanosized alloy as ~12 at.%, which is much higher than the solid solubility limit of Nb in bulk Fe. Full article
(This article belongs to the Special Issue Phase Change Material and Magnetic Research)
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11 pages, 4802 KiB  
Communication
Two One-Dimensional Copper-Oxalate Frameworks with the Jahn–Teller Effect: [(CH3)3NH]2[Cu(μ-C2O4)(C2O4)]·2.5H2O (I) and [(C2H5)3NH]2[Cu(μ-C2O4)(C2O4)]·H2O (II)
by Bin Zhang, Yan Zhang, Zheming Wang, Yang Sun, Tongling Liang, Mei Liu and Daoben Zhu
Magnetochemistry 2023, 9(5), 120; https://doi.org/10.3390/magnetochemistry9050120 - 29 Apr 2023
Viewed by 1018
Abstract
Two one-dimensional oxalate-bridged Cu(II) ammonium salts, [(CH3)3NH]2[Cu(μ-C2O4)(C2O4)]·2.5H2O (I) and [(C2H5)3NH]2[Cu(μ-C2O4)(C2O4 [...] Read more.
Two one-dimensional oxalate-bridged Cu(II) ammonium salts, [(CH3)3NH]2[Cu(μ-C2O4)(C2O4)]·2.5H2O (I) and [(C2H5)3NH]2[Cu(μ-C2O4)(C2O4)]·H2O (II) were obtained and characterized. They were composed of ammonium: (CH3)3NH+ in (I), (C2H5)3NH+ in (II), [Cu(μ-C2O4)(C2O4)2−]n and H2O. The Jahn–Teller-distorted Cu(II) is octahedrally coordinated by six O atoms from three oxalates and forms a one-dimensional zigzag chain. The hydrogen bonds between ammonium, the anion and H2O form a three-dimensional network. There is no hydrogen bond between the anion chains. They were insulated at 20 °C with a relative humidity of 40%. Ferromagnetic and weak-ferromagnetic behaviors were observed in I and II, separately. No long-range ordering was observed above 2 K. Full article
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10 pages, 1892 KiB  
Article
Superconducting Gap Structure of Filled Skutterudite LaOs4As12 Compound through μSR Investigations
by Amitava Bhattacharyya, Devashibhai T. Adroja, Adrian D. Hillier and Pabitra Kumar Biswas
Magnetochemistry 2023, 9(5), 117; https://doi.org/10.3390/magnetochemistry9050117 - 28 Apr 2023
Viewed by 1217
Abstract
Filled skutterudite compounds have gained attention recently as an innovative platforms for studying intriguing low-temperature superconducting properties. Regarding the symmetry of the superconducting gap, contradicting findings from several experiments have been made for LaRu4As12 and its isoelectronic counterpart, LaOs4 [...] Read more.
Filled skutterudite compounds have gained attention recently as an innovative platforms for studying intriguing low-temperature superconducting properties. Regarding the symmetry of the superconducting gap, contradicting findings from several experiments have been made for LaRu4As12 and its isoelectronic counterpart, LaOs4As12. In this vein, we report comprehensive bulk and microscopic results on LaOs4As12 utilizing specific heat analysis and muon-spin rotation/relaxation (μSR) measurements. Bulk superconductivity with TC = 3.2 K was confirmed by heat capacity. The superconducting ground state of the filled-skutterudite LaOs4As12 compound is found to have two key characteristics: superfluid density exhibits saturation type behavior at low temperature, which points to a fully gapped superconductivity with gap value of 2Δ/kBTC = 3.26; additionally, the superconducting state does not show any sign of spontaneous magnetic field, supporting the preservation of time-reversal symmetry. These results open the door for the development of La-based skutterudites as special probes for examining the interplay of single- and multiband superconductivity in classical electron–phonon systems. Full article
(This article belongs to the Section Applications of Magnetism and Magnetic Materials)
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50 pages, 3678 KiB  
Review
Diversity of Iron Oxides: Mechanisms of Formation, Physical Properties and Applications
by Kamil G. Gareev
Magnetochemistry 2023, 9(5), 119; https://doi.org/10.3390/magnetochemistry9050119 - 27 Apr 2023
Cited by 6 | Viewed by 5666
Abstract
Iron oxide compounds have naturally formed during the whole of Earth’s history. Synthetic compositions with iron oxides are produced with the use of various techniques and widely used for scientific and applied purposes. This review considers an attempt to classify all the information [...] Read more.
Iron oxide compounds have naturally formed during the whole of Earth’s history. Synthetic compositions with iron oxides are produced with the use of various techniques and widely used for scientific and applied purposes. This review considers an attempt to classify all the information on different iron oxide compound formation mechanisms and intended applications in biomedicine, catalysis, waste remediation, geochemistry, etc. All the literature references analyzed were divided into several groups by their number of included iron oxide compounds: compositions containing only one compound (e.g., magnetite or wüstite), including various polymorphs of iron(III) oxide (α-, β-, γ-, ε-, ζ-, δ-Fe2O3); compositions with two different distinguishable iron oxide phases (e.g., maghemite and hematite); compositions containing non-crystalline phases (amorphous iron oxide or atomic clusters); and compositions with mixed iron oxide phases (indistinguishable separate iron oxide phases). Diagrams on the distribution of the literature references between various iron oxide compounds and between various applications were built. Finally, the outlook on the perspectives of further iron oxide studies is provided. Full article
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13 pages, 4938 KiB  
Communication
MHD Hybrid Nanofluid Flow over a Stretching/Shrinking Sheet with Skin Friction: Effects of Radiation and Mass Transpiration
by Angadi Basettappa Vishalakshi, Rudraiah Mahesh, Ulavathi Shettar Mahabaleshwar, Alaka Krishna Rao, Laura M. Pérez and David Laroze
Magnetochemistry 2023, 9(5), 118; https://doi.org/10.3390/magnetochemistry9050118 - 27 Apr 2023
Cited by 5 | Viewed by 1673
Abstract
The study of inclined magnetohydrodynamics (MHD) mixed convective incompressible flow of a fluid with hybrid nanoparticles containing a colloidal combination of nanofluids and base fluid is presented in the current research. Al2O3-Cu/H2O hybrid nanofluid [...] Read more.
The study of inclined magnetohydrodynamics (MHD) mixed convective incompressible flow of a fluid with hybrid nanoparticles containing a colloidal combination of nanofluids and base fluid is presented in the current research. Al2O3-Cu/H2O hybrid nanofluid is utilized in the current analysis to enhance the heat transfer analysis. The impact of radiation is also placed at energy equation. The main research methodology includes that the problem provided equations are first transformed into non-dimensional form, and then they are obtained in ordinary differential equations (ODEs) form. Then using the solutions of momentum and transfers equations to solve the given ODEs to get the root of the equation. The main purpose includes the resulting equations are then analytically resolved with the aid of suitable boundary conditions. The results can be discussed with various physical parameters viz., stretched/shrinked-Rayleigh number, stretching/shrinking parameter, Prandtl number, etc. Besides, skin friction and heat transfer coefficient can be examined with suitable similarity transformations. The main significance of the present work is to explain the mixed convective fluid flow on the basis of analytical method. Main findings at the end we found that the transverse and tangential velocities are more for more values of stretched/shrinked-Rayleigh number and mass transpiration for both suction and injection cases. This is the special method it includes stretched/shrinked-Rayleigh number, it contributes major role in this analysis. The purpose of finding the present work is to understand the analytical solution on the basis of mixed convective method. Full article
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8 pages, 2186 KiB  
Communication
Ferroelectric Polarization in an h-BN-Encapsulated 30°-Twisted Bilayer–Graphene Heterostructure
by Lingling Ren and Baojuan Dong
Magnetochemistry 2023, 9(5), 116; https://doi.org/10.3390/magnetochemistry9050116 - 26 Apr 2023
Viewed by 1600
Abstract
Recently, the emergent two-dimensional (2D) ferroelectric materials have provided new possibilities for the miniaturization of ferroelectric systems and the integration of novel 2D nano-electronic devices. In addition to the intrinsic ferroelectrics exfoliated from bulk, 2D heterostructures hybridized from electrically non-polarized van der Waals [...] Read more.
Recently, the emergent two-dimensional (2D) ferroelectric materials have provided new possibilities for the miniaturization of ferroelectric systems and the integration of novel 2D nano-electronic devices. In addition to the intrinsic ferroelectrics exfoliated from bulk, 2D heterostructures hybridized from electrically non-polarized van der Waals (vdW) materials have also been proven to be a promising platform for the construction of ferroelectricity. Here, we report 30° twisted bilayer–graphene (TBLG) incommensurate moiré superlattice encapsulated by hexagonal boron nitride (h-BN), in which robust hysteretic resistance was detected at the top interface between h-BN and the TBLG from room temperature down to 40 mK. The hysteretic phenomenon can be understood by the extra carrier induced by the interfacial 2D ferroelectric polarization, which is estimated to be around 0.7 pC/m. Our work of interfacial ferroelectric heterostructure achieved by a TBLG/h-BN hybrid system expands the 2D ferroelectric families and opens more possibilities for future coupling the ferroelectricity with rich electronic and optical properties in vdW twistronic devices. Full article
(This article belongs to the Special Issue Advances in Magnetic Two Dimensional Materials)
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7 pages, 1589 KiB  
Communication
Effect of Co-Doping on the Magnetic Ground State of the Heavy-Fermion System CeCu2Ge2 Studied by Neutron Diffraction
by Rajesh Tripathi, Dmitry Khalyavin, Shivani Sharma, Devashibhai Thakarshibhai Adroja and Zakir Hossain
Magnetochemistry 2023, 9(5), 115; https://doi.org/10.3390/magnetochemistry9050115 - 26 Apr 2023
Viewed by 1076
Abstract
The antiferromagnetic phase transition of the heavy-fermion system Ce(Cu1xCox)2Ge2 for x = 0.05 and 0.2, showing up in specific heat, magnetic susceptibility, and muon spin relaxation (μSR) data, has been further investigated. [...] Read more.
The antiferromagnetic phase transition of the heavy-fermion system Ce(Cu1xCox)2Ge2 for x = 0.05 and 0.2, showing up in specific heat, magnetic susceptibility, and muon spin relaxation (μSR) data, has been further investigated. The neutron diffraction (ND) results show that Co-doping drastically reduces the moment size of Ce, without a qualitative change in the magnetic structure of the undoped compound CeCu2Ge2. An incommensurate magnetic propagation vector k = (0.2852, 0.2852, 0.4495) with a cycloidal magnetic structure with a Ce moment of 0.55 μB in the ab-plane has been observed for x = 0.05. Although for x = 0.2 the specific heat and magnetic susceptibility data reflect a phase transition with a broad peak and the muon relaxation rate shows a sharp peak at T = 0.9 K, our ND data dismiss the possibility of a long-range magnetic ordering down to 50 mK. The ND data, along with previously reported results for x = 0.2, are interpreted in terms of the reduced ordered state magnetic moments of the Ce3+ ion by Kondo screening and the presence of dynamical short-range magnetic correlations. Full article
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17 pages, 10529 KiB  
Article
Shielding Effectiveness Measurement Method for Planar Nanomaterial Samples Based on CNT Materials up to 18 GHz
by Andrea Amaro, Adrian Suarez, Jose Torres, Pedro A. Martinez, Roberto Herraiz, Antonio Alcarria, Adolfo Benedito, Rocio Ruiz, Pedro Galvez and Antonio Penades
Magnetochemistry 2023, 9(5), 114; https://doi.org/10.3390/magnetochemistry9050114 - 25 Apr 2023
Cited by 4 | Viewed by 2742
Abstract
The study and measurement of the shielding effectiveness (SE) of planar materials is required to predict the suitability of a certain material to form an enclosed electromagnetic shield. One of the most widely used standards for measuring the SE of planar materials is [...] Read more.
The study and measurement of the shielding effectiveness (SE) of planar materials is required to predict the suitability of a certain material to form an enclosed electromagnetic shield. One of the most widely used standards for measuring the SE of planar materials is ASMT D4935-18. It is based on a coaxial sample holder (CSH) that operates up to 1.5 GHz. Due to this standard’s frequency limitations, new variants with higher frequency limits have been developed by decreasing the size of the CSH conductors and the samples. However, this method and its high-frequency variants require two types of samples with very specific geometries and sizes. This method is unsuitable for certain types of nanomaterials due to their complex mechanization at such undersized scales. This contribution proposes an alternative SE measurement method based on an absorber box that mitigates the problems presented by the ASTM D4935-18 standard. The SE of rigid nanomaterial samples based on several concentrations of multi-walled carbon nanotubes (MWCNT) and two different fiber reinforcements have been obtained. Full article
(This article belongs to the Special Issue Magnetic Materials, Thin Films and Nanostructures)
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19 pages, 6077 KiB  
Article
Spin-Topological Electronic Valve in Ni/hBN–Graphene–hBN/Ni Magnetic Junction
by Yusuf Wicaksono, Halimah Harfah, Gagus Ketut Sunnardianto, Muhammad Aziz Majidi and Koichi Kusakabe
Magnetochemistry 2023, 9(5), 113; https://doi.org/10.3390/magnetochemistry9050113 - 25 Apr 2023
Cited by 1 | Viewed by 1069
Abstract
A spin-topological electronic valve was discovered in a Ni/hBN–graphene–hBN/Ni magnetic junction to control the in-plane conductance of graphene. By manipulating the mass-gapped Dirac cone (MGDC) of graphene’s topology using the magnetic proximity effect, the spin-topological electronic valve was made possible. The first-principles investigation [...] Read more.
A spin-topological electronic valve was discovered in a Ni/hBN–graphene–hBN/Ni magnetic junction to control the in-plane conductance of graphene. By manipulating the mass-gapped Dirac cone (MGDC) of graphene’s topology using the magnetic proximity effect, the spin-topological electronic valve was made possible. The first-principles investigation was conducted to show how the mechanism of graphene’s MGDC is controlled. Twelve stacking configurations for the anti-parallel configuration (APC) and parallel configuration (PC) of the magnetic alignment of Ni slabs were calculated using spin-polarized density functional theory. Three groups can be made based on the relative total energy of the 12 stacking configurations, which corresponds to a van der Waals interaction between hBN and graphene. Each group exhibits distinctive features of graphene’s MGDC. The configuration of the Ni(111) surface state’s interaction with graphene as an evanescent wave significantly impacts how the MGDC behaves. By utilizing the special properties of graphene’s MGDC, which depend on the stacking configuration, a controllable MGDC using mechanical motion was proposed by suggesting a device that can translate the top and bottom Ni(111)/hBN slabs. By changing the stacking configuration from Group I to II and II to III, three different in-plane conductances of graphene were observed, corresponding to three non-volatile memory states. This device provides insight into MJs having three or more non-volatile memory states that cannot be found in conventional MJs. Full article
(This article belongs to the Special Issue New Trends in Spintronic Materials and Devices)
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16 pages, 2174 KiB  
Article
A Simulation Independent Analysis of Single- and Multi-Component cw ESR Spectra
by Aritro Sinha Roy, Boris Dzikovski, Dependu Dolui, Olga Makhlynets, Arnab Dutta and Madhur Srivastava
Magnetochemistry 2023, 9(5), 112; https://doi.org/10.3390/magnetochemistry9050112 - 23 Apr 2023
Cited by 1 | Viewed by 1501
Abstract
The accurate analysis of continuous-wave electron spin resonance (cw ESR) spectra of biological or organic free-radicals and paramagnetic metal complexes is key to understanding their structure–function relationships and electrochemical properties. The current methods of analysis based on simulations often fail to extract the [...] Read more.
The accurate analysis of continuous-wave electron spin resonance (cw ESR) spectra of biological or organic free-radicals and paramagnetic metal complexes is key to understanding their structure–function relationships and electrochemical properties. The current methods of analysis based on simulations often fail to extract the spectral information accurately. In addition, such analyses are highly sensitive to spectral resolution and artifacts, users’ defined input parameters and spectral complexity. We introduce a simulation-independent spectral analysis approach that enables broader application of ESR. We use a wavelet packet transform-based method for extracting g values and hyperfine (A) constants directly from cw ESR spectra. We show that our method overcomes the challenges associated with simulation-based methods for analyzing poorly/partially resolved and unresolved spectra, which is common in most cases. The accuracy and consistency of the method are demonstrated on a series of experimental spectra of organic radicals and copper–nitrogen complexes. We showed that for a two-component system, the method identifies their individual spectral features even at a relative concentration of 5% for the minor component. Full article
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