scholarly journals Ab initioperiodic approach to electronic structure and magnetic exchange inA2CuO2X2(A=Ca,Sr andX=F,Cl)high-Tcsuperconductor parent compounds

2003 ◽  
Vol 67 (13) ◽  
Author(s):  
Ibério de P. R. Moreira ◽  
Roberto Dovesi
Keyword(s):  
Electronic Structure ◽  
Magnetic Exchange

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

Structural analysis of Gd6FeBi2 from single-crystal X-ray diffraction methods and electronic structure calculations

2019 ◽  
Vol 75 (5) ◽  
pp. 562-567 ◽  
Author(s):  
Jiliang Zhang ◽  
Yong-Mook Kang ◽  
Guangcun Shan ◽  
Svilen Bobev
Keyword(s):  
Electronic Structure ◽  
Single Crystal ◽  
First Principles ◽  
Earth Metal ◽  
Magnetic Ordering ◽  
Additional Contribution ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
Magnetic Exchange ◽  
X Ray

The crystal structure of the gadolinium iron bismuthide Gd6FeBi2 has been characterized by single-crystal X-ray diffraction data and analyzed in detail using first-principles calculations. The structure is isotypic with the Zr6CoAl2 structure, which is a variant of the ZrNiAl structure and its binary prototype Fe2P (Pearson code hP9, Wyckoff sequence g f d a). As such, the structure is best viewed as an array of tricapped trigonal prisms of Gd atoms centered alternately by Fe and Bi. The magnetic-ordering temperature of this compound (ca 350 K) is much higher than that of other rare-earth metal-rich phases with the same or related structures. It is also higher than the ordering temperature of many other Gd-rich ternary phases, where the magnetic exchange is typically governed by Ruderman–Kittel–Kasuya–Yosida (RKKY) interactions. First-principles calculations reveal a larger than expected Gd magnetic moment, with the additional contribution arising from the Gd 5d electrons. The electronic structure analysis suggests strong Gd 5d–Fe 3d hybridization to be the cause of this effect, rather than weak interactions between Gd and Bi. These details are of importance for understanding the magnetic response and explaining the high ordering temperature in this material.

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 Electronic structure and magnetic exchange coupling in ferromagnetic full Heusler alloys

2005 ◽  
Vol 71 (1) ◽  
Author(s):  
Yasemin Kurtulus ◽  
Richard Dronskowski ◽  
German D. Samolyuk ◽  
Vladimir P. Antropov
Keyword(s):  
Electronic Structure ◽  
Exchange Coupling ◽  
Heusler Alloys ◽  
Magnetic Exchange ◽  
Magnetic Exchange Coupling ◽  
Full Heusler ◽  
Full Heusler Alloys

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>

Understanding Magnetic Exchange in Molecule-Based Magnets from an Electronic Structure Point of View

2015 ◽  
pp. 203-246
Author(s):  
Andrew Weber ◽  
Paul Rulis ◽  
Michelle Paquette ◽  
Konstantin Pohkhodyna ◽  
Saad Janjua ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Point Of View ◽  
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>

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