Electronic structure and effective chemical and magnetic exchange interactions in bcc Fe-Cr alloys

2009 ◽  
Vol 79 (5) ◽  
Author(s):  
P. A. Korzhavyi ◽  
A. V. Ruban ◽  
J. Odqvist ◽  
J.-O. Nilsson ◽  
B. Johansson
Keyword(s):  
Electronic Structure ◽  
Exchange Interactions ◽  
Magnetic Exchange

scholarly journals Improved electronic structure and magnetic exchange interactions in transition metal oxides

2017 ◽  
Vol 29 (44) ◽  
pp. 444003 ◽  
Author(s):  
Priya Gopal ◽  
Riccardo De Gennaro ◽  
Marta Silva dos Santos Gusmao ◽  
Rabih Al Rahal Al Orabi ◽  
Haihang Wang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Exchange Interactions ◽  
Magnetic Exchange

scholarly journals First Principle Investigations of Long-range Magnetic Exchange Interactions via Polyacene Coupler

2021 ◽  
Author(s):  
Prabhleen Kaur ◽  
Md. Ehesan Ali
Keyword(s):  
Wave Function ◽  
Electronic Structure ◽  
Long Range ◽  
Density Functional ◽  
Energy Gap ◽  
Exchange Interactions ◽  
Higher Order ◽  
Hybrid Functional ◽  
Magnetic Exchange ◽  
Benzene Rings

<div>The electronic and magnetic properties of polyacenes become quite fascinating as the number of linearly conjugated benzene rings increases. Higher-order conjugated polyacenes develop radicaloid characters due to the transition of electronic structures from closed-shell to the open-shell system. Here we have investigated the role of such polyacenes as the magnetic coupler when placed between the two spin-sources based on nitroxy radicals. To do so, the magnetic exchange interactions (<i>2J</i>) are computed employing electronic structure theories, i.e. broken-symmetry (BS) approach within the density functional theory (DFT) as well as symmetry-adopted wave function based multi-configurational methods. In the former approach, various genre of exchange-correlation (XC) functionals such as generalized gradient approximation (GGA), meta-GGA, hybrid functional, constrained spin density (i.e. CDFT) and on-site Coulomb correlation corrected GGA+<i>U</i> functionals are adopted. All DFT based calculations estimate an exponential increase in <i>2J</i> values with the length of the couplers, especially for the higher-order acenes. This is indeed an unexpected observation and also there is no experimental report available in support of the DFT calculations. The complexity in the electronic structure enhances with the increasing number of benzene rings due to an increase in near-degenerate or quasi-degenerate molecular orbitals (MOs) and also the reduction of the energy gap with the low-lying excited states. Consequently, it invokes a severe challenge in the computations of the magnetic exchange interactions in DFT. As an alternative approach, the wave function based multi-reference calculations, e.g. CASSCF/NEVPT2 methods are also adopted. In the later calculations, it has been realized that the π-orbitals of the couplers play a crucial role in the exchange interactions. For larger polyacenes (i.e. hexacene to decacene) such calculations become prohibitively expensive and rigorous as the number of π-orbitals increases, thus expanding the active space enormously. The limited active spaces calculations indicate quite strong ferromagnetic exchange interactions, thus <i>in principle,</i> reinforcing long-range magnetic exchange interactions.</div>

scholarly journals First Principle Investigations of Long-range Magnetic Exchange Interactions via Polyacene Coupler

2021 ◽  
Author(s):  
Prabhleen Kaur ◽  
Md. Ehesan Ali
Keyword(s):  
Wave Function ◽  
Electronic Structure ◽  
Long Range ◽  
Density Functional ◽  
Energy Gap ◽  
Exchange Interactions ◽  
Higher Order ◽  
Hybrid Functional ◽  
Magnetic Exchange ◽  
Benzene Rings

<div>The electronic and magnetic properties of polyacenes become quite fascinating as the number of linearly conjugated benzene rings increases. Higher-order conjugated polyacenes develop radicaloid characters due to the transition of electronic structures from closed-shell to the open-shell system. Here we have investigated the role of such polyacenes as the magnetic coupler when placed between the two spin-sources based on nitroxy radicals. To do so, the magnetic exchange interactions (<i>2J</i>) are computed employing electronic structure theories, i.e. broken-symmetry (BS) approach within the density functional theory (DFT) as well as symmetry-adopted wave function based multi-configurational methods. In the former approach, various genre of exchange-correlation (XC) functionals such as generalized gradient approximation (GGA), meta-GGA, hybrid functional, constrained spin density (i.e. CDFT) and on-site Coulomb correlation corrected GGA+<i>U</i> functionals are adopted. All DFT based calculations estimate an exponential increase in <i>2J</i> values with the length of the couplers, especially for the higher-order acenes. This is indeed an unexpected observation and also there is no experimental report available in support of the DFT calculations. The complexity in the electronic structure enhances with the increasing number of benzene rings due to an increase in near-degenerate or quasi-degenerate molecular orbitals (MOs) and also the reduction of the energy gap with the low-lying excited states. Consequently, it invokes a severe challenge in the computations of the magnetic exchange interactions in DFT. As an alternative approach, the wave function based multi-reference calculations, e.g. CASSCF/NEVPT2 methods are also adopted. In the later calculations, it has been realized that the π-orbitals of the couplers play a crucial role in the exchange interactions. For larger polyacenes (i.e. hexacene to decacene) such calculations become prohibitively expensive and rigorous as the number of π-orbitals increases, thus expanding the active space enormously. The limited active spaces calculations indicate quite strong ferromagnetic exchange interactions, thus <i>in principle,</i> reinforcing long-range magnetic exchange interactions.</div>

scholarly journals Electronic structure and magnetic exchange interactions of Cr-based van der Waals ferromagnets. A comparative study between CrBr3 and Cr2Ge2Te6

2020 ◽  
Vol 8 (39) ◽  
pp. 13582-13589 ◽  
Author(s):  
Adolfo O. Fumega ◽  
S. Blanco-Canosa ◽  
H. Babu-Vasili ◽  
P. Gargiani ◽  
Hongze Li ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Electronic Structure ◽  
Comparative Study ◽  
Ab Initio ◽  
Van Der Waals ◽  
Exchange Interactions ◽  
Magnetic Exchange ◽  
Microscopic Mechanism

Ab initio calculations and high-pressure experiments unveil the microscopic mechanism behind the magnetic properties of two Cr-based van der Waals ferromagnets that have different electronic structure.

Electronic structure and magnetic exchange interactions in Zn diluted CuFe2O4 magneto-ceramics

2020 ◽  
Vol 128 (7) ◽  
pp. 073908
Author(s):  
Suchit Kumar Jena ◽  
Deep Chandra Joshi ◽  
Zhuo Yan ◽  
Yajun Qi ◽  
Sayandeep Ghosh ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Exchange Interactions ◽  
Magnetic Exchange

A new 1-1-4 pattern of magnetic exchange interactions in a cubane core tetranuclear copper (II) complex

Polyhedron ◽  
2021 ◽  
Vol 199 ◽  
pp. 115088
Author(s):  
Azadeh Mehrani ◽  
Maurice G. Sorolla ◽  
Tatyana Makarenko ◽  
Allan J. Jacobson
Keyword(s):  
Exchange Interactions ◽  
Magnetic Exchange

scholarly journals Isotropic Nature of the Metallic Kagome Ferromagnet Fe3Sn2 at High Temperatures

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 307
Author(s):  
Rebecca L. Dally ◽  
Daniel Phelan ◽  
Nicholas Bishop ◽  
Nirmal J. Ghimire ◽  
Jeffrey W. Lynn
Keyword(s):  
Elevated Temperatures ◽  
Magnetocrystalline Anisotropy ◽  
Inelastic Neutron Scattering ◽  
Exchange Interactions ◽  
Inelastic Neutron ◽  
Temperature Threshold ◽  
Magnetic Exchange ◽  
Spatial Anisotropy ◽  
Isotropic Exchange ◽  
State Spin

Anisotropy and competing exchange interactions have emerged as two central ingredients needed for centrosymmetric materials to exhibit topological spin textures. Fe3Sn2 is thought to have these ingredients as well, as it has recently been discovered to host room temperature skyrmionic bubbles with an accompanying topological Hall effect. We present small-angle inelastic neutron scattering measurements that unambiguously show that Fe3Sn2 is an isotropic ferromagnet below TC≈660 K to at least 480 K—the lower temperature threshold of our experimental configuration. Fe3Sn2 is known to have competing magnetic exchange interactions, correlated electron behavior, weak magnetocrystalline anisotropy, and lattice (spatial) anisotropy; all of these features are thought to play a role in stabilizing skyrmions in centrosymmetric systems. Our results reveal that at the elevated temperatures measured, there is an absence of significant magnetocrystalline anisotropy and that the system behaves as a nearly ideal isotropic exchange interaction ferromagnet, with a spin stiffness D(T=480 K)=168 meV Å2, which extrapolates to a ground state spin stiffness D(T=0 K)=231 meV Å2.

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 Heisenberg and anisotropic exchange interactions in magnetic materials with correlated electronic structure and significant spin-orbit coupling

2021 ◽  
Vol 103 (17) ◽  
Author(s):  
Vladislav Borisov ◽  
Yaroslav O. Kvashnin ◽  
Nikolaos Ntallis ◽  
Danny Thonig ◽  
Patrik Thunström ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Magnetic Materials ◽  
Exchange Interactions ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Anisotropic Exchange

scholarly journals Magnetic exchange interactions in the van der Waals layered antiferromagnet MnPSe3

2021 ◽  
Vol 103 (2) ◽  
Author(s):  
S. Calder ◽  
A. V. Haglund ◽  
A. I. Kolesnikov ◽  
D. Mandrus
Keyword(s):  
Van Der Waals ◽  
Exchange Interactions ◽  
Magnetic Exchange
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