Magnetic Anisotropy

A special issue of Magnetochemistry (ISSN 2312-7481).

Deadline for manuscript submissions: closed (31 March 2016) | Viewed by 48065

Special Issue Editors


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Laboratory of Inorganic Chemistry, Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta nr. 4-12, Bucharest, Romania
Interests: molecular magnetism; crystal engineering; metallosupramolecular chemistry; homo- and hetero-polynuclear complexes
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Theory of Nanomaterials Group, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
Interests: molecular magnetism; magnetic anisotropy; quantum chemistry calculations; single-molecule magnets
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Magnetic anisotropy is a parameter that plays a crucial role for the occurrence of slow relaxation of magnetization in Single Molecule Magnets and Single Chain Magnets. Therefore, an understanding of the factors influencing magnetic anisotropy is an important step in the effort to design such systems. In spite of the progress achieved in the last few years, through combined experimental and theoretical studies, we still need new information in order to better tune and control anisotropy, and, ultimately, to increase the performance of molecular nano-magnets. The new journal, Magnetochemistry, now offers you an excellent forum for the presentation of your achievements in any of the topics listed below.

Prof. Dr. Marius Andruh
Prof. Dr. Liviu F. Chibotaru
Guest Editors

Manuscript Submission Information

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Keywords

  • experimental techniques for the study of magnetic anisotropy
  • theoretical models for the determination of single ion magnetic anisotropy
  • ab initio calculations of magnetic anisotropy
  • magnetic anisotropy in exchanged-coupled systems
  • lanthanide- and actinide-based molecular nanomagnets
  • magnetic relaxation pathways
  • positive anisotropy and slow relaxation of magnetization

Published Papers (7 papers)

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Research

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1797 KiB  
Article
Tools for Predicting the Nature and Magnitude of Magnetic Anisotropy in Transition Metal Complexes: Application to Co(II) Complexes
by Benjamin Cahier, Rémi Maurice, Hélène Bolvin, Talal Mallah and Nathalie Guihéry
Magnetochemistry 2016, 2(3), 31; https://doi.org/10.3390/magnetochemistry2030031 - 3 Aug 2016
Cited by 39 | Viewed by 7926
Abstract
This work addresses the question of the identification of the excited states that are mainly responsible for the magnitude and nature of the magnetic anisotropy in high-spin mononuclear transition metal complexes. Only few states are actually responsible for the single ion magnetic anisotropy, [...] Read more.
This work addresses the question of the identification of the excited states that are mainly responsible for the magnitude and nature of the magnetic anisotropy in high-spin mononuclear transition metal complexes. Only few states are actually responsible for the single ion magnetic anisotropy, and these states can be anticipated from rather simple rules. We show that in high-spin complexes atomic selection rules still prevail and that molecular selection rules from the symmetry point group are more selective than those of the double group. The predictive power of these rules is exemplified on a penta-coordinate Co(II) complex investigated with correlated ab initio calculations, including relativistic contributions. The electronic structure of excited states coupled to the ground state through spin-orbit coupling informs us about the nature (either axial or planar) of their contribution to the anisotropy. From this information, it is possible to anticipate the nature and strength of the ligand field and predict the magnetic anisotropy, which may guide the synthesis of improved anisotropic complexes. Such results can also be used to improve the quality of ab initio calculations of the spin Hamiltonian parameters and to reduce the computational cost. Full article
(This article belongs to the Special Issue Magnetic Anisotropy)
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1369 KiB  
Article
Multiple Magnetization Reversal Channels Observed in a 3d-4f Single Molecule Magnet
by Asma Amjad, Albert Figuerola, Andrea Caneschi and Lorenzo Sorace
Magnetochemistry 2016, 2(2), 27; https://doi.org/10.3390/magnetochemistry2020027 - 14 Jun 2016
Cited by 12 | Viewed by 4806
Abstract
The present study discusses the magnetic dynamics of a previously reported cyanide bridged 3d-4f dinuclear DyIIICoIII complex. Following the axial anisotropy suggested by previous Electron Paramagnetic Resonance spectroscopy (EPR) analysis, the complex turned out to show slow relaxation of the [...] Read more.
The present study discusses the magnetic dynamics of a previously reported cyanide bridged 3d-4f dinuclear DyIIICoIII complex. Following the axial anisotropy suggested by previous Electron Paramagnetic Resonance spectroscopy (EPR) analysis, the complex turned out to show slow relaxation of the magnetization at cryogenic temperature, and this was studied in different temperature and field regimes. The existence of multichannel relaxation pathways that reverse the magnetization was clearly disclosed: a tentative analysis suggested that these channels can be triggered and controlled as a function of applied static magnetic field and temperature. Persistent evidence of a temperature independent process even at higher fields, attributable to quantum tunneling, is discussed, while the temperature dependent dynamics is apparently governed by an Orbach process. The broad distribution of relaxation rates evidenced by the ac susceptibility measurements suggest a relevant role of the intermolecular interactions in this system. Full article
(This article belongs to the Special Issue Magnetic Anisotropy)
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3792 KiB  
Communication
Slow Magnetic Relaxation in Unprecedented Mono-Dimensional Coordination Polymer of Ytterbium Involving Tetrathiafulvalene-Dicarboxylate Linker
by Anjara Belio Castro, Julie Jung, Stéphane Golhen, Boris Le Guennic, Lahcène Ouahab, Olivier Cador and Fabrice Pointillart
Magnetochemistry 2016, 2(2), 26; https://doi.org/10.3390/magnetochemistry2020026 - 11 May 2016
Cited by 17 | Viewed by 5085
Abstract
A one-dimensional compound has been constructed through a YbIII ion and bridging redox-active deprotonated 4,5-bis(carboxylic)-4′,5′-methyldithiotetrathiafulvene. This polymer displays slow magnetic relaxation due to the planar magnetic anisotropy of the YbIII, which has been experimentally determined. Full article
(This article belongs to the Special Issue Magnetic Anisotropy)
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1338 KiB  
Article
Torque-Detected Electron Spin Resonance as a Tool to Investigate Magnetic Anisotropy in Molecular Nanomagnets
by María Dörfel, Michal Kern, Heiko Bamberger, Petr Neugebauer, Katharina Bader, Raphael Marx, Andrea Cornia, Tamoghna Mitra, Achim Müller, Martin Dressel, Lapo Bogani and Joris Van Slageren
Magnetochemistry 2016, 2(2), 25; https://doi.org/10.3390/magnetochemistry2020025 - 6 May 2016
Cited by 5 | Viewed by 5420
Abstract
The method of choice for in-depth investigation of the magnetic anisotropy in molecular nanomagnets is high-frequency electron spin resonance (HFESR) spectroscopy. It has the benefits of high resolution and facile access to large energy splittings. However, the sensitivity is limited to about 10 [...] Read more.
The method of choice for in-depth investigation of the magnetic anisotropy in molecular nanomagnets is high-frequency electron spin resonance (HFESR) spectroscopy. It has the benefits of high resolution and facile access to large energy splittings. However, the sensitivity is limited to about 107 spins for a reasonable data acquisition time. In contrast, methods based on the measurement of the deflection of a cantilever were shown to enable single spin magnetic resonance sensitivity. In the area of molecular nanomagnets, the technique of torque detected electron spin resonance (TDESR) has been used sporadically. Here, we explore the applicability of that technique by investigating molecular nanomagnets with different types of magnetic anisotropy. We also assess different methods for the detection of the magnetic torque. We find that all types of samples are amenable to these studies, but that sensitivities do not yet rival those of HFESR. Full article
(This article belongs to the Special Issue Magnetic Anisotropy)
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7199 KiB  
Article
Evidence of Slow Magnetic Relaxation in Co(AcO)2(py)2(H2O)2
by James P. S. Walsh, Graeme Bowling, Ana-Maria Ariciu, Nur F. M. Jailani, Nicholas F. Chilton, Paul G. Waddell, David Collison, Floriana Tuna and Lee J. Higham
Magnetochemistry 2016, 2(2), 23; https://doi.org/10.3390/magnetochemistry2020023 - 20 Apr 2016
Cited by 35 | Viewed by 6823
Abstract
The monometallic pseudo-octahedral complex, [Co(H2O)2(CH3COO)2(C5H5N)2], is shown to exhibit slow magnetic relaxation under an applied field of 1500 Oe. The compound is examined by a combination of experimental and [...] Read more.
The monometallic pseudo-octahedral complex, [Co(H2O)2(CH3COO)2(C5H5N)2], is shown to exhibit slow magnetic relaxation under an applied field of 1500 Oe. The compound is examined by a combination of experimental and computational techniques in order to elucidate the nature of its electronic structure and slow magnetic relaxation. We demonstrate that any sensible model of the electronic structure must include a proper treatment of the first-order orbital angular momentum, and we find that the slow magnetic relaxation can be well described by a two-phonon Raman process dominating at high temperature, with a temperature independent quantum tunnelling pathway being most efficient at low temperature. Full article
(This article belongs to the Special Issue Magnetic Anisotropy)
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2772 KiB  
Article
1D Chains of Lanthanoid Ions and a Dithienylethene Ligand Showing Slow Relaxation of the Magnetization
by Mudasir Ahmad Yatoo, Goulven Cosquer, Masakazu Morimoto, Masahiro Irie, Brian K. Breedlove and Masahiro Yamashita
Magnetochemistry 2016, 2(2), 21; https://doi.org/10.3390/magnetochemistry2020021 - 31 Mar 2016
Cited by 13 | Viewed by 4783
Abstract
Three isostructural 1D lanthanoid complexes with the general formula {[Ln2(DTE)(H-DTE)(MeOH)2]·2H2O}n (Ln = Tb, Dy, and Yb; DTE = 1,2-bis(5-carboxyl-2-methyl-3-thienyl) perfluorocyclopentene) were synthesized. In the 1D chain structure of each complex, lanthanide ions are seven coordinate with [...] Read more.
Three isostructural 1D lanthanoid complexes with the general formula {[Ln2(DTE)(H-DTE)(MeOH)2]·2H2O}n (Ln = Tb, Dy, and Yb; DTE = 1,2-bis(5-carboxyl-2-methyl-3-thienyl) perfluorocyclopentene) were synthesized. In the 1D chain structure of each complex, lanthanide ions are seven coordinate with a capped trigonal prism geometry. The 1,2-bis(5-carboxyl-2-methyl-3-thienyl) perfluorocyclopentene (DTE) ligand adopts a parallel configuration in these complexes, which results in the loss of the photo-isomerization ability of the ligand. From magnetic measurements, each complex undergoes slow relaxation of the magnetization via multiple processes in a dc field. Full article
(This article belongs to the Special Issue Magnetic Anisotropy)
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Review

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4636 KiB  
Review
Ferromagnetic Multilayers: Magnetoresistance, Magnetic Anisotropy, and Beyond
by Conrad Rizal, Belaid Moa and Boris B. Niraula
Magnetochemistry 2016, 2(2), 22; https://doi.org/10.3390/magnetochemistry2020022 - 16 Apr 2016
Cited by 30 | Viewed by 12306
Abstract
Obtaining highly sensitive ferromagnetic, FM, and nonmagnetic, NM, multilayers with a large room-temperature magnetoresistance, MR, and strong magnetic anisotropy, MA, under a small externally applied magnetic field, H, remains a subject of scientific and technical interest. Recent advances in nanofabrication and characterization techniques [...] Read more.
Obtaining highly sensitive ferromagnetic, FM, and nonmagnetic, NM, multilayers with a large room-temperature magnetoresistance, MR, and strong magnetic anisotropy, MA, under a small externally applied magnetic field, H, remains a subject of scientific and technical interest. Recent advances in nanofabrication and characterization techniques have further opened up several new ways through which MR, sensitivity to H, and MA of the FM/NM multilayers could be dramatically improved in miniature devices such as smart spin-valves based biosensors, non-volatile magnetic random access memory, and spin transfer torque nano-oscillators. This review presents in detail the fabrication and characterization of a few representative FM/NM multilayered films—including the nature and origin of MR, mechanism associated with spin-dependent conductivity and artificial generation of MA. In particular, a special attention is given to the Pulsed-current deposition technique and on the potential industrial applications and future prospects. FM multilayers presented in this review are already used in real-life applications such as magnetic sensors in automobile and computer industries. These material are extremely important as they have the capability to efficiently replace presently used magnetic sensors in automobile, electronics, biophysics, and medicine, among many others. Full article
(This article belongs to the Special Issue Magnetic Anisotropy)
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