The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform
Takashi Mizokawa - One of the best experts on this subject based on the ideXlab platform.
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Impact of Local Lattice Disorder on Spin and Orbital Orders in Ca2-xSrxRuO4
Journal of the Physical Society of Japan, 2013Co-Authors: Takuya Sugimoto, D. Ootsuki, Takashi MizokawaAbstract:We have studied relationship between local lattice disorder, Ru \(4d\) spin–orbit interaction, and global spin/orbital orders of Ca2-xSrxRuO4 in the Sr- and Ca-rich regions of its phase diagram by using Unrestricted Hartree–Fock Calculation on a \(8\times 8\) RuO4 lattice model. The Calculations show that the local elongation of RuO6 octahedron in an antiferromagnetic insulator Ca2RuO4 induces local orbital change with making the Mott gap narrower. On the other hand, local compression of RuO6 octahedron in a paramagnetic metal Sr2RuO4 induces global antiferromagnetic or ferromagnetic states. This result is consistent with a recent systematic \(\mu\)SR study by Carlo et al. which has revealed the static antiferromagnetic order at low temperature in the Sr-rich region.
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Spin-Charge-Orbital Ordering in Hollandite-Type Manganites Studied by Model Hartree-Fock Calculation
Journal of the Physical Society of Japan, 2013Co-Authors: Makoto Fukuzawa, D. Ootsuki, Takashi MizokawaAbstract:We have studied spin–charge–orbital orderings in a Mn3+/Mn4+ mixed valence state on a hollandite-type lattice using Unrestricted Hartree–Fock Calculation on a multi-band Mn \(3d\)–O \(2p\) lattice model. The Calculations show that all the Mn3+–Mn4+, Mn3+–Mn3+, and Mn4+–Mn4+ superexchange interactions are ferromagnetic and play important roles to stabilize the charge and orbital ordering patterns. The most stable charge and orbital ordering pattern is consistent with the \(1\times 1\times 1\) orthorhombic or monoclinic structure of K1.6Mn8O16.
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Spin-charge-orbital ordering in hollandite-type manganites studied by model Hartree-Fock Calculation
arXiv: Strongly Correlated Electrons, 2013Co-Authors: Makoto Fukuzawa, D. Ootsuki, Takashi MizokawaAbstract:We investigate spin-charge-orbital ordering in a Mn$^{3+}$/Mn$^{4+}$ mixed valence state on a hollandite-type lattice using Unrestricted Hartree-Fock Calculation on a multi-band Mn 3$d$-O 2$p$ lattice model. The Calculations show that the Mn$^{3+}$-Mn$^{4+}$ double exchange interaction, the Mn$^{3+}$-Mn$^{3+}$ and Mn$^{4+}$-Mn$^{4+}$ superexchange interactions are ferromagnetic and play important roles to stabilize the charge and orbital ordering pattern. The most stable charge and orbital ordering pattern is consistent with the $1\times1\times1$ orthorhombic or monoclinic structure of K$_{1.6}$Mn$_8$O$_{16}$.
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Optical response and electronic structure of Zn-doped MgAl2O4
Journal of Applied Physics, 2007Co-Authors: K. Izumi, Takashi Mizokawa, E. HanamuraAbstract:We have studied the optical response and the electronic structure of Zn-doped MgAl2O4 using optical transmission, emission, and excitation spectroscopies, x-ray photoemission spectroscopy, and Unrestricted Hartree-Fock Calculation. Emission lines at 710, 650, and 470nm observed in pure MgAl2O4 are related to the Mg vacancies and Mg–Al antisite defects. Interestingly, the intensities of these emission lines are enhanced by Zn doping. Unrestricted Hartree-Fock Calculation for Zn-doped MgAl2O4 shows that in-gap impurity states are formed just above the valence-band maximum of MgAl2O4 when the Zn ion is substituted for the B-site Al ion. On the other hand, no in-gap state is formed when the Zn ion is substituted for the A-site Mg ion. The position of the Zn (3d) impurity level is identified by the photoemission measurement. The broad spectral features of the defect-induced states in pure MgAl2O4 is dramatically reduced by the Zn doping, indicating that holes supplied from the Zn ions at B site are trapped by ...
D. Ootsuki - One of the best experts on this subject based on the ideXlab platform.
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Impact of Local Lattice Disorder on Spin and Orbital Orders in Ca2-xSrxRuO4
Journal of the Physical Society of Japan, 2013Co-Authors: Takuya Sugimoto, D. Ootsuki, Takashi MizokawaAbstract:We have studied relationship between local lattice disorder, Ru \(4d\) spin–orbit interaction, and global spin/orbital orders of Ca2-xSrxRuO4 in the Sr- and Ca-rich regions of its phase diagram by using Unrestricted Hartree–Fock Calculation on a \(8\times 8\) RuO4 lattice model. The Calculations show that the local elongation of RuO6 octahedron in an antiferromagnetic insulator Ca2RuO4 induces local orbital change with making the Mott gap narrower. On the other hand, local compression of RuO6 octahedron in a paramagnetic metal Sr2RuO4 induces global antiferromagnetic or ferromagnetic states. This result is consistent with a recent systematic \(\mu\)SR study by Carlo et al. which has revealed the static antiferromagnetic order at low temperature in the Sr-rich region.
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Spin-Charge-Orbital Ordering in Hollandite-Type Manganites Studied by Model Hartree-Fock Calculation
Journal of the Physical Society of Japan, 2013Co-Authors: Makoto Fukuzawa, D. Ootsuki, Takashi MizokawaAbstract:We have studied spin–charge–orbital orderings in a Mn3+/Mn4+ mixed valence state on a hollandite-type lattice using Unrestricted Hartree–Fock Calculation on a multi-band Mn \(3d\)–O \(2p\) lattice model. The Calculations show that all the Mn3+–Mn4+, Mn3+–Mn3+, and Mn4+–Mn4+ superexchange interactions are ferromagnetic and play important roles to stabilize the charge and orbital ordering patterns. The most stable charge and orbital ordering pattern is consistent with the \(1\times 1\times 1\) orthorhombic or monoclinic structure of K1.6Mn8O16.
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Spin-charge-orbital ordering in hollandite-type manganites studied by model Hartree-Fock Calculation
arXiv: Strongly Correlated Electrons, 2013Co-Authors: Makoto Fukuzawa, D. Ootsuki, Takashi MizokawaAbstract:We investigate spin-charge-orbital ordering in a Mn$^{3+}$/Mn$^{4+}$ mixed valence state on a hollandite-type lattice using Unrestricted Hartree-Fock Calculation on a multi-band Mn 3$d$-O 2$p$ lattice model. The Calculations show that the Mn$^{3+}$-Mn$^{4+}$ double exchange interaction, the Mn$^{3+}$-Mn$^{3+}$ and Mn$^{4+}$-Mn$^{4+}$ superexchange interactions are ferromagnetic and play important roles to stabilize the charge and orbital ordering pattern. The most stable charge and orbital ordering pattern is consistent with the $1\times1\times1$ orthorhombic or monoclinic structure of K$_{1.6}$Mn$_8$O$_{16}$.
Makoto Fukuzawa - One of the best experts on this subject based on the ideXlab platform.
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Spin-Charge-Orbital Ordering in Hollandite-Type Manganites Studied by Model Hartree-Fock Calculation
Journal of the Physical Society of Japan, 2013Co-Authors: Makoto Fukuzawa, D. Ootsuki, Takashi MizokawaAbstract:We have studied spin–charge–orbital orderings in a Mn3+/Mn4+ mixed valence state on a hollandite-type lattice using Unrestricted Hartree–Fock Calculation on a multi-band Mn \(3d\)–O \(2p\) lattice model. The Calculations show that all the Mn3+–Mn4+, Mn3+–Mn3+, and Mn4+–Mn4+ superexchange interactions are ferromagnetic and play important roles to stabilize the charge and orbital ordering patterns. The most stable charge and orbital ordering pattern is consistent with the \(1\times 1\times 1\) orthorhombic or monoclinic structure of K1.6Mn8O16.
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Spin-charge-orbital ordering in hollandite-type manganites studied by model Hartree-Fock Calculation
arXiv: Strongly Correlated Electrons, 2013Co-Authors: Makoto Fukuzawa, D. Ootsuki, Takashi MizokawaAbstract:We investigate spin-charge-orbital ordering in a Mn$^{3+}$/Mn$^{4+}$ mixed valence state on a hollandite-type lattice using Unrestricted Hartree-Fock Calculation on a multi-band Mn 3$d$-O 2$p$ lattice model. The Calculations show that the Mn$^{3+}$-Mn$^{4+}$ double exchange interaction, the Mn$^{3+}$-Mn$^{3+}$ and Mn$^{4+}$-Mn$^{4+}$ superexchange interactions are ferromagnetic and play important roles to stabilize the charge and orbital ordering pattern. The most stable charge and orbital ordering pattern is consistent with the $1\times1\times1$ orthorhombic or monoclinic structure of K$_{1.6}$Mn$_8$O$_{16}$.
K. H. Bennemann - One of the best experts on this subject based on the ideXlab platform.
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Unrestricted Hartree-Fock Calculation of the Ionization Potential of Small Hgn Clusters
EPL, 1993Co-Authors: A. A. Aligia, Martin E. Garcia, K. H. BennemannAbstract:The ionization potential of small Hg, clusters has been calculated. For the first time good agreement with experimental results has been obtained. It is shown that interatomic Coulomb interactions are important. The energy of Hg; is calculated using the Unrestricted inhomogeneous Hartree-Fock approximation. As a consequence of a change in the charge distribution in Hg; , we obtain an abrupt change in the slope of the ionization potential at the critical cluster size ncr --- 14. The presented results are expected to be valid for covalent clusters in between ionized van der Waals clusters and metallic clusters. The size dependence of the electronic properties of small clusters is an important problem in cluster physics. Particularly interesting is the transition from van der Waals (VDW) to covalent to metallic bonding in neutral Hg, clusters for increasing cluster size (1-5). The nature of the chemical bonding in Hg; clusters remains unclear. The positive charge may be either localized within a subcluster Hg,' (i ~ n), as in ionized VDW systems (3,6, 7), or delocalized, as in ionized metallic clusters. Therefore, it is important to study the ionization potential (IP), since it reflects the combined properties of the neutral and ionized clusters. Experiments (1,3) show an abrupt change in the slope of the IP of Hgn clusters for n; -.. 13. It is the purpose of this letter to calculate the IP(n) of Hg, clusters, taking into account explicitly the properties of the ionized clusters. Atwo-band Hubbard Hamiltonian including interatomic Coulomb repulsion, charge-dipole and dipole-depole interactions between nearest neighbours (n.n.) is used:
María A. H. Vozmediano - One of the best experts on this subject based on the ideXlab platform.
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Pinning and switching of magnetic moments in bilayer graphene
New Journal of Physics, 2009Co-Authors: Eduardo V. Castro, M. P. López-sancho, María A. H. VozmedianoAbstract:We examine the magnetic properties of the localized states induced by lattice vacancies in bilayer graphene with an Unrestricted Hartree–Fock Calculation. We show that, with realistic values of the parameters and for experimentally accessible gate voltages, we can have magnetic switching between an unpolarized and a fully polarized system.
