Condensed Matter

19 pages, 11149 KiB

Open AccessArticle

The Cryogenic Anticoincidence Detector for the NewAthena X-IFU Instrument: A Program Overview

by Claudio Macculi, Andrea Argan, Matteo D’Andrea, Simone Lotti, Gabriele Minervini, Luigi Piro, Lorenzo Ferrari Barusso, Corrado Boragno, Edvige Celasco, Giovanni Gallucci, Flavio Gatti, Daniele Grosso, Manuela Rigano, Fabio Chiarello, Guido Torrioli, Mauro Fiorini, Michela Uslenghi, Daniele Brienza, Elisabetta Cavazzuti, Simonetta Puccetti, Angela Volpe and Paolo Bastia Show full author list Hide full author list

Condens. Matter 2023, 8(4), 108; https://doi.org/10.3390/condmat8040108 - 13 Dec 2023

Cited by 4 | Viewed by 1473

Abstract

Athena (advanced telescope for high-energy astrophysics) is an ESA large-class mission, at present under a re-definition “design-to-cost” phase, planned for a prospective launch at L1 orbit in the second half of the 2030s. It will be an observatory alternatively focusing on two complementary [...] Read more.

Athena (advanced telescope for high-energy astrophysics) is an ESA large-class mission, at present under a re-definition “design-to-cost” phase, planned for a prospective launch at L1 orbit in the second half of the 2030s. It will be an observatory alternatively focusing on two complementary instruments: the X-IFU (X-ray Integral Field Unit), a TES (TransitionEdge Sensor)-based kilo-pixel array which is able to perform simultaneous high-grade energy spectroscopy (~3 eV@7 keV) and imaging over 4′ FoV (field of view), and the WFI (Wide Field Imager), which has good energy spectral resolution (~170 eV@7 keV) and imaging on wide 40′ × 40′ FoV. Athena will be a truly transformational observatory, operating in conjunction with other large observatories across the electromagnetic spectrum available in the 2030s like ALMA, ELT, JWST, SKA, CTA, etc., and in multi-messenger synergies with facilities like LIGO A+, Advanced Virgo+, LISA, IceCube and KM3NeT. The Italian team is involved in both instruments. It has the co-PIship of the cryogenic instrument for which it has to deliver the TES-based Cryogenic AntiCoincidence detector (CryoAC) necessary to guarantee the X-IFU sensitivity, degraded by a primary particle background of both solar and galactic cosmic ray (GCR) origins, and by secondary electrons produced by primaries interacting with the materials surrounding the main detector. The outcome of Geant4 studies shows the necessity for adopting both active and passive techniques to guarantee the residual particle background at 5 × 10⁻³ cts cm⁻² s⁻¹ keV⁻¹ level in 2–10 keV scientific bandwidth. The CryoAC is a four-pixel detector made of Si-suspended absorbers sensed by Ir/Au TESes placed at <1 mm below the main detector. After a brief overview of the Athena mission, we will report on the particle background reduction techniques highlighting the impact of the Geant4 simulation on the X-IFU focal plane assembly design, then hold a broader discussion on the CryoAC program in terms of detection chain system requirements, test, design concept against trade-off studies and programmatic. Full article

(This article belongs to the Special Issue High Precision X-ray Measurements 2023)

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9 pages, 874 KiB

Open AccessArticle

Single-Band versus Two-Band Description of Magnetism in Infinite-Layer Nickelates

by Tharathep Plienbumrung, Maria Daghofer, Jean-Baptiste Morée and Andrzej M. Oleś

Condens. Matter 2023, 8(4), 107; https://doi.org/10.3390/condmat8040107 - 06 Dec 2023

Viewed by 1211

Abstract

We present a weak-coupling analysis of magnetism in infinite-layer nickelates, where we compare a single-band description with a two-band model. Both models predict that (i) hybridization due to hopping is negligible, and (

i i

) the magnetic properties are characterized [...] Read more.

We present a weak-coupling analysis of magnetism in infinite-layer nickelates, where we compare a single-band description with a two-band model. Both models predict that (i) hybridization due to hopping is negligible, and (

i i

) the magnetic properties are characterized by very similar dynamic structure factors,

S (\vec{k}, ω)

, at the points

(π, π, 0)

and

(π, π, π)

. This gives effectively a two-dimensional description of the magnetic properties. Full article

(This article belongs to the Special Issue Superstripes Physics, 2nd Edition)

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11 pages, 1688 KiB

Open AccessArticle

Impact of Solid-State Charge Injection on Spectral Photoresponse of NiO/Ga₂O₃ p–n Heterojunction

by Alfons Schulte, Sushrut Modak, Yander Landa, Atman Atman, Jian-Sian Li, Chao-Ching Chiang, Fan Ren, Stephen J. Pearton and Leonid Chernyak

Condens. Matter 2023, 8(4), 106; https://doi.org/10.3390/condmat8040106 - 02 Dec 2023

Viewed by 1446

Abstract

Forward bias hole injection from 10-nm-thick p-type nickel oxide layers into 10-μm-thick n-type gallium oxide in a vertical NiO/Ga₂O₃ p–n heterojunction leads to enhancement of photoresponse of more than a factor of 2 when measured from this junction. While it [...] Read more.

Forward bias hole injection from 10-nm-thick p-type nickel oxide layers into 10-μm-thick n-type gallium oxide in a vertical NiO/Ga₂O₃ p–n heterojunction leads to enhancement of photoresponse of more than a factor of 2 when measured from this junction. While it takes only 600 s to obtain such a pronounced increase in photoresponse, it persists for hours, indicating the feasibility of photovoltaic device performance control. The effect is ascribed to a charge injection-induced increase in minority carrier (hole) diffusion length (resulting in improved collection of photogenerated non-equilibrium carriers) in n-type β-Ga₂O₃ epitaxial layers due to trapping of injected charge (holes) on deep meta-stable levels in the material and the subsequent blocking of non-equilibrium carrier recombination through these levels. Suppressed recombination leads to increased non-equilibrium carrier lifetime, in turn determining a longer diffusion length and being the root-cause of the effect of charge injection. Full article

(This article belongs to the Special Issue Wide-Band-Gap Semiconductors for Energy and Electronics)

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33 pages, 9786 KiB

Open AccessReview

Advances in P(VDF-TrFE) Composites: A Methodical Review on Enhanced Properties and Emerging Electronics Applications

by Lekshmi Priya P S, Biswaranjan Swain, Shailendra Rajput, Saubhagyalaxmi Behera and Sabyasachi Parida

Condens. Matter 2023, 8(4), 105; https://doi.org/10.3390/condmat8040105 - 01 Dec 2023

Viewed by 1939

Abstract

Piezoelectric polymers are a class of material that belong to carbon–hydrogen-based organic materials with a long polymer chain. They fill the void where single crystals and ceramics fail to perform. This characteristic of piezoelectric polymers made them unique. Their piezoelectric stress constant is [...] Read more.

Piezoelectric polymers are a class of material that belong to carbon–hydrogen-based organic materials with a long polymer chain. They fill the void where single crystals and ceramics fail to perform. This characteristic of piezoelectric polymers made them unique. Their piezoelectric stress constant is higher than ceramics and the piezoelectric strain is lower compared to ceramics. This study’s goal is to present the most recent information on poly(vinylidene fluoride) with trifluoroethylene P(VDF-TrFE), a major copolymer of poly(vinylidene fluoride) PVDF with piezoelectric, pyroelectric, and ferroelectric characteristics. The fabrication of P(VDF-TrFE) composites and their usage in a variety of applications, including in actuators, transducers, generators, and energy harvesting, are the primary topics of this work. The report provides an analysis of how the addition of fillers improves some of the features of P(VDF-TrFE). Commonly utilized polymer composite preparation techniques, including spinning, Langmuir–Blodgett (LB), solution casting, melt extrusion, and electrospinning are described, along with their effects on the pertinent characteristics of the polymer composite. A brief discussion on the literature related to different applications (such as bio-electronic devices, sensors and high energy-density piezoelectric generators, low mechanical damping, and easy voltage rectifiers of the polymer composite is also presented. Full article

(This article belongs to the Special Issue New Advances in Condensed Matter Physics)

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16 pages, 4940 KiB

Open AccessArticle

Hybrid Superconducting/Superconducting Mesoscopic Heterostructure Studied by Modified Ginzburg–Landau Equations

by Jesús González, Angélica Melendez and Luis Camargo

Condens. Matter 2023, 8(4), 104; https://doi.org/10.3390/condmat8040104 - 01 Dec 2023

Viewed by 1099

Abstract

Studies involving vortexes in hybrid superconducting devices and their interactions with different components inside samples are important for reaching higher values of critical parameters in superconducting materials. The vortex distribution on each side of a sample with different fundamental parameters, such as temperature [...] Read more.

Studies involving vortexes in hybrid superconducting devices and their interactions with different components inside samples are important for reaching higher values of critical parameters in superconducting materials. The vortex distribution on each side of a sample with different fundamental parameters, such as temperature T, penetration depth

λ

, coherence length

ξ

, electron mass m, and the order parameter

Ψ

, may help to improve the superconducting properties. Thus, in this work, we used the modified Ginzburg–Landau theory to investigate a hybrid superconductor (HS), as well as to provide a highly tunable and adjustable theoretical tool for theoretically explaining the experimental results involving the HS in order to study the vortex behavior in superconductors of mesoscopic dimensions with extreme differences among their fundamental parameters. Therefore, we evaluated the influence of the HS on the vortex configuration and its effects on field-dependent magnetization. The results show that when the applied magnetic field H was increased, the diamagnetic response of the HS (Meissner effect) included additional jumps in magnetization, while diamagnetism continued to increase in the sample. In addition, the differences among parameters created an interface between both components, and two different magnitudes of supercurrent and vortex sizes caused less degradation of the local superconductivity, which increased the upper critical field. On the other hand, this type of HS with differences in parameters on both sides can be used to control the vortex movement in the selected sample of the superconducting region with more accuracy. Full article

(This article belongs to the Special Issue Multicomponent Superconductivity and Superfluidity)

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13 pages, 8992 KiB

Open AccessArticle

Fluorescence and Raman Micro-Spectroscopy of LiF Films Containing Radiation-Induced Defects for X-ray Detection

by Francesca Bonfigli, Sabina Botti, Maria Aurora Vincenti, Rosa Maria Montereali, Alessandro Rufoloni, Pasquale Gaudio and Riccardo Rossi

Condens. Matter 2023, 8(4), 103; https://doi.org/10.3390/condmat8040103 - 30 Nov 2023

Viewed by 1278

Abstract

Lithium fluoride (LiF) film detectors for extreme ultraviolet radiation, soft and hard X-rays, based on the photoluminescence of radiation-induced electronic defects, have been proposed and are currently under further development and investigation. LiF film detectors are versatile and can be integrated in different [...] Read more.

Lithium fluoride (LiF) film detectors for extreme ultraviolet radiation, soft and hard X-rays, based on the photoluminescence of radiation-induced electronic defects, have been proposed and are currently under further development and investigation. LiF film detectors are versatile and can be integrated in different experimental apparatus and imaging configurations. LiF can be grown in the form of polycrystalline thin films and it is compatible with several substrates. The radiation-induced color center (CCs) photoluminescence (PL) response can be enhanced through the appropriate choice of substrates and multilayer designs, and by tailoring the micro-structural properties of polycrystalline LiF films through the control of the growth conditions. In this work, we present the characterization, through fluorescence and Raman micro-spectroscopy, of LiF films, thermally evaporated on different substrates with thicknesses of up to 1 μm, irradiated with soft X-rays produced by a laser plasma source. The combination of these micro-spectroscopy techniques could represent an advanced method to investigate the role of the polycrystalline film structures in CC formation efficiency at the microscopic level, a fundamental aspect of the development of LiF film radiation-imaging detectors. Full article

(This article belongs to the Special Issue High Precision X-ray Measurements 2023)

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18 pages, 6003 KiB

Open AccessArticle

Effect of Growth and Calcination Temperatures on the Optical Properties of Ruthenium-Doped ZnO Nanoparticles

by Dema Dasuki, Khulud Habanjar and Ramdan Awad

Condens. Matter 2023, 8(4), 102; https://doi.org/10.3390/condmat8040102 - 29 Nov 2023

Viewed by 2088

Abstract

This study aimed to probe the effect of heat treatment on zinc oxide nanoparticles doped with ruthenium through a chemical co-preparation technique. Pure ZnO and Ru-doped ZnO nanoparticles, with the general formula Zn_1−x−Ru_xO, were synthesized for 0 ≤ x [...] Read more.

This study aimed to probe the effect of heat treatment on zinc oxide nanoparticles doped with ruthenium through a chemical co-preparation technique. Pure ZnO and Ru-doped ZnO nanoparticles, with the general formula Zn_1−x−Ru_xO, were synthesized for 0 ≤ x ≤ 0.04. Using the same starting precursors, the growth temperature was 60 °C and 80 °C for set A and set B, respectively, whereas the calcination temperature was 450 °C and 550 °C for set A and set B, respectively. For the structure investigation, X-ray powder diffraction (XRD) revealed that the crystallite size of set A was smaller than that of set B. For x = 0.04 in set B, the maximum value of the crystallite size was attributed to the integration of Ru³⁺ ions into interstitial sites in the host causing this expansion. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of zinc oxide nanoparticles by showing a Zn-O bonding peak at 421 cm⁻¹. For x = 0.04 in set B, the divergence confirmed the change in bonding properties of Zn²⁺ distributed by Ru³⁺ doping, which verifies the presence of secondary-phase RuO₂. Using UV–visible spectroscopy, the energy gap of set A swings as ruthenium doping increases. However, in set B, as the crystallite size decreases, the energy gap increases until reversing at the highest concentration of x = 0.04. The transition from oxygen vacancy to interstitial oxygen, which is associated with the blue peak (469 nm), increases in set A under low heating conditions and decreases in set B as Ru doping increases, as revealed in the photoluminescence optical spectra of the samples. Therefore, ruthenium doping proves a useful surface defect and generates distortion centers in the lattice, leading to more adsorption and a remarkable advantage in sunscreen and paint products used for UV protection. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))

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13 pages, 2051 KiB

Open AccessArticle

Improving the Time Resolution of Large-Area LaBr₃:Ce Detectors with SiPM Array Readout

by Maurizio Bonesini, Roberto Bertoni, Andrea Abba, Francesco Caponio, Marco Prata and Massimo Rossella

Condens. Matter 2023, 8(4), 99; https://doi.org/10.3390/condmat8040099 - 17 Nov 2023

Cited by 2 | Viewed by 1201

Abstract

LaBr

_{3}

:Ce crystals have good scintillation properties for X-ray spectroscopy. Initially, they were introduced for radiation imaging in medical physics with either a photomultiplier or SiPM readout, and they found extensive applications in homeland security and gamma-ray astronomy. We used 1

^{″}

[...] Read more.

LaBr

_{3}

:Ce crystals have good scintillation properties for X-ray spectroscopy. Initially, they were introduced for radiation imaging in medical physics with either a photomultiplier or SiPM readout, and they found extensive applications in homeland security and gamma-ray astronomy. We used 1

^{″}

round LaBr

_{3}

:Ce crystals to realize compact detectors with the SiPM array readout. The aim was a good energy resolution and a fast time response to detect low-energy X-rays around 100 keV. A natural application was found inside the FAMU experiment, at RIKEN RAL. Its aim is a precise measurement of the proton Zemach radius with impinging muons, to contribute to the solution to the so-called “proton radius puzzle”. Signals to be detected are characteristic X-rays around 130 KeV. A limit for this type of detector, as compared to the ones with a photomultiplier readout, is its poorer timing characteristics due to the large capacity of the SiPM arrays used. In particular, long signal falltimes are a problem in experiments such as FAMU, where a “prompt” background component must be separated from a “delayed” one (after 600 ns) in the signal X-rays to be detected. Dedicated studies were pursued to improve the timing characteristics of the used detectors, starting from hybrid ganging of SiPM cells; then developing a suitable zero pole circuit with a parallel ganging, where an increased overvoltage for the SiPM array was used to compensate for the signal decrease; and finally designing ad hoc electronics to split the 1

^{″}

detector’s SiPM array into four quadrants, thus reducing the involved capacitances. The aim was to improve the detectors’ timing characteristics, especially falltime, while keeping a good FWHM energy resolution for low-energy X-ray detection. Full article

(This article belongs to the Special Issue High Precision X-ray Measurements 2023)

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14 pages, 5715 KiB

Open AccessArticle

Combined Spectroscopy System Utilizing Gas Electron Multiplier and Timepix3 Technology for Laser Plasma Experiments

by Veronica De Leo, Gerardo Claps, Francesco Cordella, Gabriele Cristoforetti, Leonida Antonio Gizzi, Petra Koester, Danilo Pacella and Antonella Tamburrino

Condens. Matter 2023, 8(4), 98; https://doi.org/10.3390/condmat8040098 - 17 Nov 2023

Viewed by 1155

Abstract

We present an innovative X-ray spectroscopy system to address the complex study of the X-ray emissions arising from laser–target interactions, where the emissions occur within extremely brief intervals from femtoseconds to nanoseconds. Our system combines a Gas Electron Multiplier (GEM) detector with a [...] Read more.

We present an innovative X-ray spectroscopy system to address the complex study of the X-ray emissions arising from laser–target interactions, where the emissions occur within extremely brief intervals from femtoseconds to nanoseconds. Our system combines a Gas Electron Multiplier (GEM) detector with a silicon-based Timepix3 (TPX3) detector. These detectors work in tandem, allowing for a spectroscopic radiation analysis along the same line of sight. With an active area of 10 × 10 cm

^{2}

, the GEM detector allows for 1D measurements for X-ray energies (2–50 keV) by utilizing the full 10 cm gas depth. The high-energy part of the radiation beam exits through a downstream side window of the GEM without being absorbed in the gas volume. Positioned side-on at the GEM detector’s exit, the TPX3 detector, equipped with a pixelated sensor (55 µm × 55 µm; active area 14 mm × 14 mm), uses its full 14 mm silicon sensor to detect hard X-rays (50–500 keV) and gamma rays (0.5–10 MeV). We demonstrate the correct operation of the entire detection system and provide a detailed description of the Timepix3 detector’s calibration procedure, highlighting the suitability of the combined system to work in laser plasma facilities. Full article

(This article belongs to the Special Issue High Precision X-ray Measurements 2023)

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9 pages, 2004 KiB

Open AccessArticle

The Implementation of MuDirac in Geant4: A Preliminary Approach to the Improvement of the Simulation of the Muonic Atom Cascade Process

by Matteo Cataldo, Oliviero Cremonesi, Stefano Pozzi, Emiliano Mocchiutti, Ritabrata Sarkar, Adrian D. Hillier and Massimiliano Clemenza

Condens. Matter 2023, 8(4), 101; https://doi.org/10.3390/condmat8040101 - 17 Nov 2023

Viewed by 1404

Abstract

Muonic Atom X-ray Emission spectroscopy (µ-XES) is a novel elemental technique that exploits the high-energy X-rays emitted from the muonic atom cascade process to characterize materials. At the ISIS Neutron and Muon Source, the technique is performed at Port4 of the RIKEN-RAL facility, [...] Read more.

Muonic Atom X-ray Emission spectroscopy (µ-XES) is a novel elemental technique that exploits the high-energy X-rays emitted from the muonic atom cascade process to characterize materials. At the ISIS Neutron and Muon Source, the technique is performed at Port4 of the RIKEN-RAL facility, with a user demand that is increasing every year. To cope with this demand, it is necessary to continue to improve the method, either for the hardware (detectors, acquisition, etc.) or software (data analysis and interpretation). In both cases, Monte Carlo codes play an important role: with a simulation, it is possible to reproduce the experimental setup and provide a reliable quantitative analysis. In this work, we investigate the capabilities of GEANT4 for such applications. From the results, we observed that the generation of X-rays, especially the kα and kβ transition for high Z atoms, are not in agreement with the experimental ones. A solution to this issue, other than an attempt with a small modification of the GEANT4 cascade class, could be provided by a database of transition energy calculated by a Dirac equation software called MuDirac. The software, developed by the UKRI scientific computing department and the ISIS muon group, can compute all the transition energy for a given nuclide. Here, preliminary results of the implementation of the MuDirac database in GEANT4 are reported. Full article

(This article belongs to the Special Issue High Precision X-ray Measurements 2023)

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15 pages, 1416 KiB

Open AccessArticle

Two-Dimensional Discommensurations: An Extension to McMillan’s Ginzburg–Landau Theory

by Lotte Mertens, Jeroen van den Brink and Jasper van Wezel

Condens. Matter 2023, 8(4), 100; https://doi.org/10.3390/condmat8040100 - 17 Nov 2023

Viewed by 1331

Abstract

Charge density waves (CDWs) profoundly affect the electronic properties of materials and have an intricate interplay with other collective states, like superconductivity and magnetism. The well-known macroscopic Ginzburg–Landau theory stands out as a theoretical method for describing CDW phenomenology without requiring a microscopic [...] Read more.

Charge density waves (CDWs) profoundly affect the electronic properties of materials and have an intricate interplay with other collective states, like superconductivity and magnetism. The well-known macroscopic Ginzburg–Landau theory stands out as a theoretical method for describing CDW phenomenology without requiring a microscopic description. In particular, it has been instrumental in understanding the emergence of domain structures in several CDW compounds, as well as the influence of critical fluctuations and the evolution towards or across lock-in transitions. In this context, McMillan’s foundational work introduced discommensurations as the objects mediating the transition from commensurate to incommensurate CDWs, through an intermediate nearly commensurate phase characterised by an ordered array of phase slips. Here, we extended the simplified, effectively one-dimensional, setting of the original model to a fully two-dimensional analysis. We found exact and numerical solutions for several types of discommensuration patterns and provide a framework for consistently describing multi-component CDWs embedded in quasi-two-dimensional atomic lattices. Full article

(This article belongs to the Special Issue Superstripes Physics, 2nd Edition)

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14 pages, 510 KiB

Open AccessArticle

Topological Gauge Theory of Josephson Junction Arrays: The Discovery of Superinsulation

by Maria Cristina Diamantini

Condens. Matter 2023, 8(4), 97; https://doi.org/10.3390/condmat8040097 - 16 Nov 2023

Viewed by 1185

Abstract

We review the topological gauge theory description of Josephson junction arrays (JJA), fabricated systems which exhibit the superconductor-to-insulator transition (SIT). This description revealed the topological nature of the phases around the SIT and led to the discovery of a new state of matter, [...] Read more.

We review the topological gauge theory description of Josephson junction arrays (JJA), fabricated systems which exhibit the superconductor-to-insulator transition (SIT). This description revealed the topological nature of the phases around the SIT and led to the discovery of a new state of matter, the superinsulator, characterized by infinite resistance, even at finite temperatures, due to linear confinement of electric charges. This discovery is particularly relevant for the physics of superconducting films with emergent granularity, which are modeled with JJAs and share the same phase diagram. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))

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9 pages, 2879 KiB

Open AccessArticle

Laser Fabrication of Gold–sp-Carbon Films

by Stella Kavokina, Anton Osipov, Vlad Samyshkin, Andrey Abramov, Natalia Rozhkova, Vitali Kononenko, Vitali Konov and Alexey Kucherik

Condens. Matter 2023, 8(4), 96; https://doi.org/10.3390/condmat8040096 - 14 Nov 2023

Viewed by 1163

Abstract

We develop a method for the laser synthesis and deposition of carbon–gold films formed by a net of linear sp-carbon chains and stabilized by gold nanoparticles. The originality of the method is in the simultaneous production of carbon chains and gold nanoparticles due [...] Read more.

We develop a method for the laser synthesis and deposition of carbon–gold films formed by a net of linear sp-carbon chains and stabilized by gold nanoparticles. The originality of the method is in the simultaneous production of carbon chains and gold nanoparticles due to the laser fragmentation of the amorphous carbon and hydrogen tetrachloroaurate (III) or chloroauric acid. We study how surface resistivity alters the effect of the obtained films via the illumination in the visible spectral range. Full article

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14 pages, 396 KiB

Open AccessArticle

On the Evaluation of Higher-Harmonic-Current Responses for High-Field Spectroscopies in Disordered Superconductors

by Götz Seibold

Condens. Matter 2023, 8(4), 95; https://doi.org/10.3390/condmat8040095 - 13 Nov 2023

Viewed by 1112

Abstract

We discuss a formalism that allows for the calculation of a higher-harmonic-current response to a strong applied electric field for disordered superconducting systems described on the basis of tight-binding models with on- and/or intersite interactions. The theory is based on an expansion of [...] Read more.

We discuss a formalism that allows for the calculation of a higher-harmonic-current response to a strong applied electric field for disordered superconducting systems described on the basis of tight-binding models with on- and/or intersite interactions. The theory is based on an expansion of the density matrix in powers of the field amplitudes, where we solve the equation of motion for the individual components. This allows the evaluation of higher-order response functions on significantly larger lattices than one can achieve with a previously used approach, which is based on a direct temporal integration of the equation of motion for the complete density matrix. In the case of small lattices, where both methods can be applied by including also the contribution of collective modes, we demonstrate the agreement of the corresponding results. Full article

(This article belongs to the Special Issue Superstripes Physics, 2nd Edition)

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10 pages, 6302 KiB

Open AccessArticle

Experimental and Numerical Investigations on the Parameters of a Synchronous Machine Prototype with High-Temperature Superconductor Armature Windings

by Hocine Menana and Yazid Statra

Condens. Matter 2023, 8(4), 94; https://doi.org/10.3390/condmat8040094 - 09 Nov 2023

Viewed by 1230

Abstract

In their applications in electrical machines, high-temperature superconductors (HTSs) are mainly used as inductors in synchronous machines due to the AC losses which can lead to high cryogenic costs. In this work, we show the possibility of their use as armature windings, handling [...] Read more.

In their applications in electrical machines, high-temperature superconductors (HTSs) are mainly used as inductors in synchronous machines due to the AC losses which can lead to high cryogenic costs. In this work, we show the possibility of their use as armature windings, handling some precautions. The approach is based on the combined use of modeling and measurements. The construction and the preliminary tests of a handmade prototype of an axial field HTS synchronous machine are presented. Several tests have been conducted at liquid nitrogen temperature. The measurements have been confirmed by modeling results. The preliminary tests on the prototype, in both modeling and measurements, are very promising. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))

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11 pages, 8571 KiB

Open AccessArticle

Vortex Dynamics and Pinning in CaKFe₄As₄ Single Crystals from DC Magnetization Relaxation and AC Susceptibility

by Alina M. Ionescu, Ion Ivan, Corneliu F. Miclea, Daniel N. Crisan, Armando Galluzzi, Massimiliano Polichetti and Adrian Crisan

Condens. Matter 2023, 8(4), 93; https://doi.org/10.3390/condmat8040093 - 29 Oct 2023

Cited by 1 | Viewed by 1054

Abstract

Among various “families” of iron-based superconductors, the quite recently discovered AeAFe₄As₄ (where Ae is an alkali-earth metal and A is an alkali metal) has high critical current density, a very high upper critical field, and a low anisotropy, and [...] Read more.

Among various “families” of iron-based superconductors, the quite recently discovered AeAFe₄As₄ (where Ae is an alkali-earth metal and A is an alkali metal) has high critical current density, a very high upper critical field, and a low anisotropy, and has recently received much interest for the possibility of high magnetic field applications at the liquid hydrogen temperature. We have performed DC magnetization relaxation and frequency-dependent AC susceptibility measurements on high-quality single crystals of CaKFe₄As₄ with the aim of determining the pinning potential U*. The temperature dependence of U* displays a clear crossover between elastic creep and plastic creep. At temperatures around 27–28 K, U* has a very high value, up to 1200 K, resulting in an infinitesimally small probability of thermally activated flux jumps. From the dependence of the normalized pinning potential on irreversible magnetization, we have determined the creep exponents in the two creep regimes, which are in complete agreement with theoretical models. The estimation of the pinning potential from multifrequency AC susceptibility measurements was possible only near the critical temperature due to equipment limitations, and the resulting value is very close to the one that resulted from the magnetization relaxation data. Magnetic hysteresis loops revealed a second magnetization peak and very high values of the critical current density. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))

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27 pages, 13967 KiB

Open AccessArticle

Obtaining Boron Carbide and Nitride Matrix Nanocomposites for Neutron-Shielding and Therapy Applications

by Levan Chkhartishvili, Shio Makatsaria, Nika Gogolidze, Otar Tsagareishvili, Tamaz Batsikadze, Matlab Mirzayev, Shalva Kekutia, Vladimer Mikelashvili, Jano Markhulia, Tamaz Minashvili, Ketevan Davitadze, Natia Barbakadze, Tamar Dgebuadze, Ketevan Kochiashvili, Rusudan Tsiskarishvili and Roin Chedia

Condens. Matter 2023, 8(4), 92; https://doi.org/10.3390/condmat8040092 - 28 Oct 2023

Cited by 1 | Viewed by 1759

Abstract

The very high capture cross-section of (epi)thermal neutrons by the boron isotope ¹⁰B makes elemental boron and its compounds and composites prospective for serving as materials intensively interacting with neutron irradiation. In their nanostructured form, boron-rich materials reveal properties that improve their [...] Read more.

The very high capture cross-section of (epi)thermal neutrons by the boron isotope ¹⁰B makes elemental boron and its compounds and composites prospective for serving as materials intensively interacting with neutron irradiation. In their nanostructured form, boron-rich materials reveal properties that improve their radiation-performance characteristics. In this regard, new technologies have been proposed for the synthesis of nanocomposites with matrices of boron carbide B₄C and hexagonal boron nitride h-BN. For the first time, boron carbide-tungsten and hexagonal boron nitride–(iron,magnetite) composites were obtained, respectively, in the form of layered/sandwich structures of components B₄C and W and h-BN nanopowders coated/intercalated with magnetic nanoclusters of iron Fe or magnetite Fe₃O₄. Studying of their chemical/phase composition, structure/morphology, and some other properties leads to the conclusion that the developed B₄C–W and h-BN–(Fe,Fe₃O₄) composites would be useful for solving important problems of boron-based neutron shielding and BNCT (Boron Neutron Capture Therapy), such as attenuating the gamma-radiation accompanying the absorption of neutrons by ¹⁰B nuclei and targeted delivery of ¹⁰B nuclei, as BNCT therapeutic agents, to tumor tissues using control by an external magnetic field, respectively. Full article

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11 pages, 2277 KiB

Open AccessCommunication

The Depairing Current Density of a Fe(Se,Te) Crystal Evaluated in Presence of Demagnetizing Factors

by Armando Galluzzi, Krastyo Buchkov, Vihren Tomov, Elena Nazarova, Antonio Leo, Gaia Grimaldi, Adrian Crisan and Massimiliano Polichetti

Condens. Matter 2023, 8(4), 91; https://doi.org/10.3390/condmat8040091 - 23 Oct 2023

Viewed by 1205

Abstract

The effect of the demagnetizing factor, regarding the determination of the de-pairing current density

J_{d e p}

, has been studied in the case of a Fe(Se,Te) crystal, using DC magnetic measurements as a function of a magnetic field (H) [...] Read more.

The effect of the demagnetizing factor, regarding the determination of the de-pairing current density

J_{d e p}

, has been studied in the case of a Fe(Se,Te) crystal, using DC magnetic measurements as a function of a magnetic field (H) at different temperatures (T). First, the lower critical field

H_{c 1}

(T) values were obtained, and the demagnetization effects acting on them were investigated after calculating the demagnetizing factor. The temperature behaviors of both the original

H_{c 1}

values and the ones obtained after considering the demagnetization effects (

H_{c 1}^{d e m a g}

) were analyzed, and the temperature dependence of the London penetration depth

λ_{L}

(T) was obtained in both cases. In particular, the

λ_{L}

(T) curves were fitted with a power law dependence, indicating the presence of low-energy quasiparticle excitations. Furthermore, by plotting

λ_{L}^{- 2}

as a function of T, we found that our sample behaves as a multigap superconductor, which is similar to other Fe-11 family iron-based compounds. After that, the coherence length

ξ

values were extracted, starting with the

H_{c 2}

(T) curve. The knowledge of

λ_{L}

and

ξ

allowed us to determine the

J_{d e p}

values and to observe how they are influenced by the demagnetizing factor. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))

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9 pages, 1623 KiB

Open AccessArticle

Effects of the Exciton Fine Structure Splitting on the Entanglement-Based Quantum Key Distribution

by Adrián Felipe Hernández-Borda, María Paula Rojas-Sepúlveda and Hanz Yecid Ramírez-Gómez

Condens. Matter 2023, 8(4), 90; https://doi.org/10.3390/condmat8040090 - 10 Oct 2023

Viewed by 1300

Abstract

The reliable transmission of secure keys is one of the essential tasks to be efficiently accomplished by quantum information processing, and the use of entangled particles is a very important tool toward that goal. However, efficient production of maximally entangled states is still [...] Read more.

The reliable transmission of secure keys is one of the essential tasks to be efficiently accomplished by quantum information processing, and the use of entangled particles is a very important tool toward that goal. However, efficient production of maximally entangled states is still a challenge for further progress in quantum computing and quantum communication. In the search for optimal sources of entanglement, quantum dots have emerged as promising candidates, but the presence of dephasing in the generated entangled states raises questions about their real usefulness in large-scale quantum networks. In this work, we evaluate the effects of the exciton fine structure splitting, present in most quantum dot samples, on the fidelity of the BBM92 protocol for quantum key distribution. We find that the protocol’s performance is heavily impacted by such splitting and establish an upper limit for the product between the energy splitting and the exciton lifetime to have a dependable distributed key. Full article

(This article belongs to the Special Issue Physics of Light-Matter Coupling in Nanostructures)

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8 pages, 2820 KiB

Open AccessArticle

Suppression of Stacking Order with Doping in 1T-TaS_2−xSe_x

by Sharon S. Philip, Despina Louca, Matthew B. Stone and Alexander I. Kolesnikov

Condens. Matter 2023, 8(4), 89; https://doi.org/10.3390/condmat8040089 - 10 Oct 2023

Cited by 1 | Viewed by 1330

Abstract

In 1T-TaS

_{2 - x}

Se

_{x}

, the charge density wave (CDW) state features a star of David lattice that expands across layers as the system becomes commensurate upon cooling. The layers can also order along the c-axis, and different stacking orders [...] Read more.

In 1T-TaS

_{2 - x}

Se

_{x}

, the charge density wave (CDW) state features a star of David lattice that expands across layers as the system becomes commensurate upon cooling. The layers can also order along the c-axis, and different stacking orders have been proposed. Using neutron scattering on powder samples, we compared the stacking order previously observed in 1T-TaS

_{2}

when the system is doped with Se. While at low temperature, a 13c layer sequence stacking was observed in TaS

_{2}

; this type of ordering was not evident with doping. Doping with Se results in a metallic state in which the Mott transition is suppressed, which may be linked to the absence of layer stacking. Full article

(This article belongs to the Special Issue Superstripes Physics, 2nd Edition)

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7 pages, 506 KiB

Open AccessArticle

Ultrafast Pump–Probe Spectroscopy in Organic Dirac Electron Candidate α-(BETS)₂I₃

by Satoshi Tsuchiya, Masato Katsumi, Ryuhei Oka, Toshio Naito and Yasunori Toda

Condens. Matter 2023, 8(4), 88; https://doi.org/10.3390/condmat8040088 - 10 Oct 2023

Viewed by 1060

Abstract

Photo-induced carrier dynamics were measured in the organic Dirac electron candidate

α

-(BETS)

_{2}

I

_{3}

to investigate why resistivity increases below

T_{MI}

= 50 K. We found a change in carrier dynamics due to an insulating gap formation below

T^{'}

[...] Read more.

Photo-induced carrier dynamics were measured in the organic Dirac electron candidate

α

-(BETS)

_{2}

I

_{3}

to investigate why resistivity increases below

T_{MI}

= 50 K. We found a change in carrier dynamics due to an insulating gap formation below

T^{'}

= 50 K. On the other hand, the relaxation time and polarization anisotropy of the observed dynamics differ from those in the charge-ordering (CO) state of the isostructural salt

α

-(ET)

_{2}

I

_{3}

. Based on the difference, it can be concluded that the insulating phase has a different origin than the CO state. Full article

(This article belongs to the Special Issue Superstripes Physics, 2nd Edition)

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23 pages, 13693 KiB

Open AccessArticle

Superconducting and Mechanical Properties of the Tl_0.8Hg_0.2Ba₂Ca₂Cu₃O_9−δ Superconductor Phase Substituted by Lanthanum and Samarium Fluorides

by Rola F. Khattar, Mohammed Anas, Ramadan Awad and Khulud Habanjar

Condens. Matter 2023, 8(4), 87; https://doi.org/10.3390/condmat8040087 - 07 Oct 2023

Viewed by 974

Abstract

This study investigated the impact of samarium and lanthanum fluorides (SmF₃ and LaF₃) on the physical and mechanical properties of Tl_0.8Hg_0.2Ba₂Ca_2−xR_xCu₃O_9−δ−yF_y superconducting phases (specifically [...] Read more.

This study investigated the impact of samarium and lanthanum fluorides (SmF₃ and LaF₃) on the physical and mechanical properties of Tl_0.8Hg_0.2Ba₂Ca_2−xR_xCu₃O_9−δ−yF_y superconducting phases (specifically the (Tl, Hg)-1223 phase), where R = Sm and La, with

0.00 \leq x \leq 0.10

. The superconducting samples were synthesized using the solid-state reaction method. X-ray diffraction (XRD) verified the formation of the (Tl, Hg)-1223 phase without altering its tetragonal structure. Scanning electron micrographs (SEM) reveal the improvement of the grain size and inter-grain connectivity as Sm and La contents increased up to

x = 0.025

. The electrical properties of (Tl, Hg)-1223 were studied using I-V and electrical resistivity measurements. Improved superconducting transition temperature (T_c) and transport critical current density (J_c) were observed up to

x = 0.025

, beyond which they decreased substantially. Vickers microhardness (H_v) measurements were performed at room temperature to investigate their mechanical performance with various applied loads (

0.49 - 9.80

N) and times (

10 - 90

s). For both substitutions, the mechanical properties were enhanced up to an optimal value at

x = 0.025

. All samples exhibited normal indentation size effect (ISE) behavior. The proportional sample resistance (PSR) model best explained H_v values among five theoretical models. Dislocation creep was the primary creep mechanism in the samples, according to indentation creep studies. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))

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12 pages, 525 KiB

Open AccessArticle

Position-Dependent Effective Mass and Asymmetry Effects on the Electronic and Optical Properties of Quantum Wells with Improved Rosen–Morse Potential

by Esin Kasapoglu, Melike Behiye Yücel and Carlos A. Duque

Condens. Matter 2023, 8(4), 86; https://doi.org/10.3390/condmat8040086 - 05 Oct 2023

Cited by 2 | Viewed by 1165

Abstract

In this study, we investigated, for the first time, the effects of the spatially varying effective mass, asymmetry parameter, and well width on the electronic and optical properties of a quantum well which has an improved Rosen–Morse potential. Calculations were made within the [...] Read more.

In this study, we investigated, for the first time, the effects of the spatially varying effective mass, asymmetry parameter, and well width on the electronic and optical properties of a quantum well which has an improved Rosen–Morse potential. Calculations were made within the framework of the effective mass and parabolic band approximations. We have used the diagonalization method by choosing a wave function based on the trigonometric orthonormal functions to find eigenvalues and eigenfunctions of the electron confined within the improved Rosen–Morse potential. Our results show that the position dependence mass, asymmetry, and confinement parameters cause significant changes in the electronic and optical properties of the structure we focus on since these effects create a significant increase in electron energies and a blue shift in the absorption spectrum. The increase in energy levels enables the development of optoelectronic devices that can operate at wider wavelengths and absorb higher-energy photons. Through an appropriate choice of parameters, the Rosen–Morse potential offers, among many advantages, the possibility of simulating heterostructures close to surfaces exposed to air or vacuum, thus giving the possibility of substantially enriching the allowed optical transitions given the breaking of the system´s symmetries. Similarly, the one-dimensional Rosen–Morse potential model proposed here can be extended to one- and zero-dimensional structures such as core/shell quantum well wires and quantum dots. This offers potential advancements in fields such as optical communication, imaging technology, and solar cells. Full article

(This article belongs to the Special Issue Physics of Light-Matter Coupling in Nanostructures)

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Condens. Matter, Volume 8, Issue 4 (December 2023) – 23 articles

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