scholarly journals A heteroleptic diradical Cr(iii) complex with extended spin delocalization and large intramolecular magnetic exchange

2020 ◽  
Vol 56 (36) ◽  
pp. 4906-4909 ◽  
Author(s):  
Xiaozhou Ma ◽  
Elizaveta A. Suturina ◽  
Mathieu Rouzières ◽  
Fabrice Wilhelm ◽  
Andrei Rogalev ◽  
...  
Keyword(s):  
Magnetic Interactions ◽  
Magnetic Exchange ◽  
Spin Delocalization ◽  
Metal Radical

Ligand-based successive reductions in a heteroleptic Cr(iii) complex give rise to intended extremely strong metal–radical magnetic interactions.

scholarly journals Exploiting host–guest chemistry to manipulate magnetic interactions in metallosupramolecular M4L6 tetrahedral cages

2021 ◽  
Vol 12 (14) ◽  
pp. 5134-5142 ◽  
Author(s):  
Aaron J. Scott ◽  
Julia Vallejo ◽  
Arup Sarkar ◽  
Lucy Smythe ◽  
E. Regincós Martí ◽  
...  
Keyword(s):  
Exchange Interactions ◽  
Magnetic Interactions ◽  
Magnetic Exchange ◽  
Guest Chemistry

The tetrahedral [NiII4L6]8+ cage can reversibly bind paramagnetic MX41/2− guests, inducing magnetic exchange interactions between host and guest.

scholarly journals Assessing crystal field and magnetic interactions in diuranium-μ-chalcogenide triamidoamine complexes with UIV–E–UIV cores (E = S, Se, Te): implications for determining the presence or absence of actinide–actinide magnetic exchange

2017 ◽  
Vol 8 (9) ◽  
pp. 6207-6217 ◽  
Author(s):  
Benedict M. Gardner ◽  
David M. King ◽  
Floriana Tuna ◽  
Ashley J. Wooles ◽  
Nicholas F. Chilton ◽  
...  
Keyword(s):  
Crystal Field ◽  
Exchange Coupling ◽  
Magnetic Interactions ◽  
Magnetic Exchange ◽  
Field Effects

Analysis of UIV–E–UIV (E = S, Se, Te) complexes reveals their behaviour is due to crystal field effects and not exchange coupling.

scholarly journals Structural and Magnetic Properties of Mn-Based Diluted Magnetic Semiconductors and Alloys

2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
A. Alsaad
Keyword(s):  
Rock Salt ◽  
Diluted Magnetic Semiconductors ◽  
Magnetic Semiconductors ◽  
Exchange Interactions ◽  
Magnetic Interactions ◽  
Local Spin Density Approximation ◽  
Energy Minimum ◽  
Rock Salt Structure ◽  
Magnetic Exchange ◽  
Salt Structure

Direct supercell approach calculations of the magnetic exchange interactions in Mn-doped ScN was carried out in the local spin density approximation by using the muffin-tin-orbital Green's function method. We found that magnetic interactions are long range interactions and affected by the randomness, band gap corrections, and carrier concentrations. Using total energy minimization approach we found that the global energy minimum of MnN is obtained for zinc-blende structure. If the compound is compressed by 6%, the energy minimum corresponds to the rock-salt structure in disagreement with the experimentally observed tetragonal distorted rock-salt structure, known as -phase. An isostructural phase transition for alloys from MnN -phase to -ScN phase was found to occur at a hydrostatic pressure of 18 GPa. We predict above room temperature for Mn concentrations of about 10% in ScN : Mn system.

scholarly journals Exploring through-bond and through-space magnetic communication in 1,3,2-dithiazolyl radical complexes

2019 ◽  
Vol 55 (66) ◽  
pp. 9849-9852
Author(s):  
Dominique Leckie ◽  
Nadia T. Stephaniuk ◽  
Ana Arauzo ◽  
Javier Campo ◽  
Jeremy M. Rawson
Keyword(s):  
Exchange Coupling ◽  
Molecular Packing ◽  
Magnetic Exchange ◽  
Metal Radical

Coordination of the dithiazolyl radical MBDTA leads to strong intramolecular metal–radical magnetic exchange but the strength of the intermolecular exchange coupling is strongly dependent on molecular packing.

scholarly journals Theory of lattice effects on magnetic interactions in solids

2005 ◽  
Author(s):  
◽  
Hakim Meskine
Keyword(s):  
Industrial Applications ◽  
Magnetic Interactions ◽  
Magnetic Polaron ◽  
Magnetic Exchange ◽  
Hard Drives ◽  
Site Model ◽  
Lattice Coupling ◽  
Storage Batteries ◽  
Main Ideas ◽  
Fast Memory

This dissertation focuses on studying the effect of lattice distortions on the magnetic properties of nickelates and manganites. These two families of materials have great potential in industrial applications in the fields of magnetic (superdense hard-drives, fast memory) and charge storage (batteries). The introduction and methods sections present the main ideas of the dissertation and discuss the various techniques used. Electron-lattice coupling is first examined in chapter three for a two-site model where we estimate the magnitude of the isotope effect on the critical temperature and show that it decreases magnetic exchange. In the next part we study electronic structure and magnetism of NaNiO2 and show that inter-planar exchange is reduced by lattice coupling. In the fifth chapter we examine the magnetic polaron and discuss the effect of static lattice coupling on its binding energy, and find it to further stabilize the polaron.

scholarly journals Exploiting Host-Guest Chemistry to Manipulate Magnetic Interactions in Metallosupramolecular M4L6 Tetrahedral Cages

2021 ◽  
Author(s):  
Aaron Scott ◽  
Julia Vallejo ◽  
Arup Sarkar ◽  
Lucy Smythe ◽  
Emma Regincós Martí ◽  
...  
Keyword(s):  
Single Crystal ◽  
Self Assembly ◽  
Close Agreement ◽  
Exchange Interactions ◽  
Magnetic Interactions ◽  
Magnetic Exchange ◽  
Guest Molecules ◽  
Space Groups ◽  
Comparable Magnitude ◽  
Spin Densities

<p>Reaction of Ni(OTf)<sub>2</sub> with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [Ni<sup>II</sup><sub>4</sub>L<sub>6</sub>]<sup>8+</sup>. By selectively exchanging the bound triflate from [OTfÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>7</sub> (<b>1</b>), we have been able to prepare a series of host-guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [M<sup>II</sup>X<sub>4</sub>ÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>6</sub>, where M<sup>II</sup>X<sub>4</sub><sup>2− </sup>= MnCl<sub>4</sub><sup>2−</sup> (<b>2</b>), CoCl<sub>4</sub><sup>2−</sup> (<b>5</b>), CoBr<sub>4</sub><sup>2−</sup> (<b>6</b>), NiCl<sub>4</sub><sup>2−</sup> (<b>7</b>), CuBr<sub>4</sub><sup>2−</sup> (<b>8</b>) or [M<sup>III</sup>X<sub>4</sub>ÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>7</sub>, where M<sup>III</sup>X<sub>4</sub><sup>−</sup> = FeCl<sub>4</sub><sup>−</sup> (<b>3</b>), FeBr<sub>4</sub><sup>−</sup> (<b>4</b>). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host-guest complexes <b>1</b>-<b>8</b> all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN<sub>6</sub>} vertex within a single Ni<sub>4</sub>L<sub>6</sub> unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [Ni<sup>II</sup><sub>4</sub>] complex, and between the host and the MX<sub>4</sub><sup>n-</sup> guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular {MX<sub>4</sub>}<sup>n−</sup> guest molecules leads to stronger host-guest magnetic exchange interactions. </p>

scholarly journals Substrate-Controlled Magnetism: Fe Nanowires on Vicinal Cu Surfaces

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 159 ◽  
Author(s):  
D. Hashemi ◽  
M. J. Waters ◽  
W. Hergert ◽  
J. Kieffer ◽  
V. S. Stepanyuk
Keyword(s):  
Density Functional ◽  
Magnetic Coupling ◽  
Atomic Scale ◽  
Magnetic Interactions ◽  
Critical Temperatures ◽  
Magnetic Exchange ◽  
Functional Theory ◽  
Novel Approach ◽  
The Stability ◽  
Exchange Parameters

Here we present a novel approach to controlling magnetic interactions between atomic-scale nanowires. Our ab initio calculations demonstrate the possibility to tune magnetic properties of Fe nanowires formed on vicinal Cu surfaces. Both intrawire and interwire magnetic exchange parameters are extracted from density functional theory (DFT) calculations. This study suggests that the effective interwire magnetic exchange parameters exhibit Ruderman–Kittel–Kasuya–Yosida-like (RKKY) oscillations as a function of Fe interwire separation. The choice of the vicinal Cu surface offers possibilities for controlling the magnetic coupling. Furthermore, an anisotropic Heisenberg model was used in Monte Carlo simulations to examine the stability of these magnetic configurations at finite temperatures. The predicted critical temperatures of the Fe nanowires on Cu(422) and Cu(533) surfaces are well above room temperature.

scholarly journals Determining the range of magnetic interactions from the relations between magnon eigenvalues at high-symmetry k points

2021 ◽  
Author(s):  
Di Wang ◽  
Jihai Yu ◽  
Feng Tang ◽  
Yuan Li ◽  
Xiangang Wan
Keyword(s):  
Magnetic Moments ◽  
A Priori ◽  
Exchange Interactions ◽  
Wave Theory ◽  
Real Space ◽  
Simple Relation ◽  
Magnetic Interactions ◽  
High Symmetry ◽  
Magnetic Exchange ◽  
The Fourier Transform

Abstract Magnetic exchange interactions (MEIs) define networks of coupled magnetic moments and lead to a surprisingly rich variety of their magnetic properties. Typically MEIs can be estimated by fitting experimental results. But how many MEIs need to be included in the fitting process for a material is not clear a priori, which limits the quality of results obtained by these conventional methods. In this paper, based on linear spin-wave theory but without performing matrix diagonalization, we show that for a general quadratic spin Hamiltonian, there is a simple relation between the Fourier transform of MEIs and the sum of square of magnon energies (SSME). We further show that according to the real-space distance range within which MEIs are considered relevant, one can obtain the corresponding relationships between SSME in momentum space. We also develop a theoretical tool for tabulating the rule about SSME. By directly utilizing these characteristics and the experimental magnon energies at only a few high-symmetry k points in the Brillouin zone, one can obtain strong constraints about the range of exchange path beyond which MEIs can be safely neglected. Our methodology is also general applicable for other Hamiltonian with quadratic Fermi or Boson operators.

Ab initio investigation of the structural and magnetic properties of Ni-Pt-Mn-Ga alloys

2013 ◽  
Vol 1581 ◽  
Author(s):  
Mikhail A. Zagrebin ◽  
Vladimir V. Sokolovskiy ◽  
Vasiliy D. Buchelnikov ◽  
Peter Entel ◽  
Sergey V. Taskaev
Keyword(s):  
Experimental Data ◽  
Magnetic Properties ◽  
Theoretical Calculations ◽  
Magnetic Interactions ◽  
Cubic Phase ◽  
Magnetic Exchange ◽  
Field Methods ◽  
Spin Polarized ◽  
Self Consistent Field ◽  
Structural And Magnetic Properties

ABSTRACTStructural and magnetic properties of Ni2-xPtxMnGa alloys are investigated from first principles calculations with the help of the spin-polarized relativistic Korringa-Kohn-Rostoker and Plane-Wave Self-Consistent Field methods. The atomic chemical disorder at specific site has been implemented using coherent potential approximation. Calculated equilibrium lattice parameters are in a good agreement with experimental data and other theoretical calculations. The composition dependences of the magnetic exchange couplings and the Curie temperature for cubic phase are obtained. Our calculations have shown that an increase content of Pt results to decrease of magnetic interactions between Mn atoms and to change of interaction sign from ferromagnetic type to antiferromagnetic one for composition Ni1.0Pt1.0MnGa. Calculated Curie temperatures are in an agreement with experimental data.

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