The Experts below are selected from a list of 103986 Experts worldwide ranked by ideXlab platform
Oskar Vafek - One of the best experts on this subject based on the ideXlab platform.
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space group Symmetry Spin orbit coupling and the low energy effective hamiltonian for iron based superconductors
Physical Review B, 2013Co-Authors: Vladimir Cvetkovic, Oskar VafekAbstract:We construct the Symmetry adapted low-energy effective Hamiltonian for the electronic states in the vicinity of the Fermi level in iron-based superconductors. We use Luttinger's method of invariants, expanding about $\ensuremath{\Gamma}$ and $M$ points in the Brillouin zone corresponding to a two-iron unit cell, and then matching the coefficients of the expansion to the five- and eight-band models. We then use the method of invariants to study the effects of the Spin-density wave order parameters on the electronic spectrum, with and without Spin-orbit coupling included. Among the results of this analysis is the finding that the nodal Spin-density wave is unstable once Spin-orbit coupling is included. Similar analysis is performed for the ${A}_{1g}$ Spin singlet superconducting state. Without Spin-orbit coupling there is one pairing invariant near the $\ensuremath{\Gamma}$ point but two near the $M$ point. This leads to an isotropic spectral gap at the hole Fermi surface near $\ensuremath{\Gamma}$, but anisotropic near $M$. The relative values of these three parameters determine whether the superconducting state is ${s}_{++}$, ${s}_{+\ensuremath{-}}$, or nodal. Inclusion of Spin-orbit coupling leads to additional mixing of Spin triplet pairing, with one additional pairing parameter near $\ensuremath{\Gamma}$ and one near $M$. This leads to an anisotropic spectral gap near both hole and electron Fermi surfaces, the latter no longer cross but rather split.
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space group Symmetry Spin orbit coupling and the low energy effective hamiltonian for iron based superconductors
Physical Review B, 2013Co-Authors: Vladimir Cvetkovic, Oskar VafekAbstract:We construct the Symmetry adapted low energy effective Hamiltonian for the electronic states in the vicinity of the Fermi level in iron based superconductors. We use Luttinger's method of invariants, expanding about Gamma and M points in the Brillouin zone corresponding to two iron unit cell, and then matching the coefficients of the expansion to the 5- and 8-band models. We then use the method of invariants to study the effects of the Spin-density wave order parameters on the electronic spectrum, with and without Spin-orbit coupling included. Among the results of this analysis is the finding that the nodal Spin-density wave is unstable once Spin-orbit coupling is included. Similar analysis is performed for the A_{1g} Spin singlet superconducting state. Without Spin-orbit coupling there is one pairing invariant near the Gamma point, but two near the M point. This leads to an isotropic spectral gap at the hole Fermi surface near Gamma, but anisotropic near M. The relative values of these three parameters determine whether the superconducting state is s_{++}, s_{+-}, or nodal. Inclusion of Spin-orbit coupling leads to additional mixing of Spin triplet pairing, with one additional pairing parameter near Gamma and one near M. This leads to an anisotropic spectral gap near both hole and electron Fermi surfaces, the latter no longer cross, but rather split.
Vladimir Cvetkovic - One of the best experts on this subject based on the ideXlab platform.
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space group Symmetry Spin orbit coupling and the low energy effective hamiltonian for iron based superconductors
Physical Review B, 2013Co-Authors: Vladimir Cvetkovic, Oskar VafekAbstract:We construct the Symmetry adapted low-energy effective Hamiltonian for the electronic states in the vicinity of the Fermi level in iron-based superconductors. We use Luttinger's method of invariants, expanding about $\ensuremath{\Gamma}$ and $M$ points in the Brillouin zone corresponding to a two-iron unit cell, and then matching the coefficients of the expansion to the five- and eight-band models. We then use the method of invariants to study the effects of the Spin-density wave order parameters on the electronic spectrum, with and without Spin-orbit coupling included. Among the results of this analysis is the finding that the nodal Spin-density wave is unstable once Spin-orbit coupling is included. Similar analysis is performed for the ${A}_{1g}$ Spin singlet superconducting state. Without Spin-orbit coupling there is one pairing invariant near the $\ensuremath{\Gamma}$ point but two near the $M$ point. This leads to an isotropic spectral gap at the hole Fermi surface near $\ensuremath{\Gamma}$, but anisotropic near $M$. The relative values of these three parameters determine whether the superconducting state is ${s}_{++}$, ${s}_{+\ensuremath{-}}$, or nodal. Inclusion of Spin-orbit coupling leads to additional mixing of Spin triplet pairing, with one additional pairing parameter near $\ensuremath{\Gamma}$ and one near $M$. This leads to an anisotropic spectral gap near both hole and electron Fermi surfaces, the latter no longer cross but rather split.
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space group Symmetry Spin orbit coupling and the low energy effective hamiltonian for iron based superconductors
Physical Review B, 2013Co-Authors: Vladimir Cvetkovic, Oskar VafekAbstract:We construct the Symmetry adapted low energy effective Hamiltonian for the electronic states in the vicinity of the Fermi level in iron based superconductors. We use Luttinger's method of invariants, expanding about Gamma and M points in the Brillouin zone corresponding to two iron unit cell, and then matching the coefficients of the expansion to the 5- and 8-band models. We then use the method of invariants to study the effects of the Spin-density wave order parameters on the electronic spectrum, with and without Spin-orbit coupling included. Among the results of this analysis is the finding that the nodal Spin-density wave is unstable once Spin-orbit coupling is included. Similar analysis is performed for the A_{1g} Spin singlet superconducting state. Without Spin-orbit coupling there is one pairing invariant near the Gamma point, but two near the M point. This leads to an isotropic spectral gap at the hole Fermi surface near Gamma, but anisotropic near M. The relative values of these three parameters determine whether the superconducting state is s_{++}, s_{+-}, or nodal. Inclusion of Spin-orbit coupling leads to additional mixing of Spin triplet pairing, with one additional pairing parameter near Gamma and one near M. This leads to an anisotropic spectral gap near both hole and electron Fermi surfaces, the latter no longer cross, but rather split.
Czeslaw Rudowicz - One of the best experts on this subject based on the ideXlab platform.
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low Symmetry Spin hamiltonian and crystal field tensors analysis fe3 in natrolite
Journal of Magnetic Resonance, 2002Co-Authors: V M Vinokurov, G R Bulka, N M Khasanova, N M Nizamutdinov, A A Galeev, Jessica May G. Gaite, Czeslaw RudowiczAbstract:Electron paramagnetic resonance study of a natural single crystal of natrolite was carried out at the frequency ν=36.772 GHz at room temperature. The angular dependence of the four Symmetry-related spectra of Fe3+ in the three crystallographic planes was fitted to a Spin Hamiltonian (S=5/2) of Symmetry Ci. The rank 4 crystal field tensors at tetrahedral sites were calculated using the point-charge model to determine the principal axes orientations of their cubic and trigonal components. The analysis of zero-field splitting tensors and comparison with crystal field ones suggests that Fe3+ substitutes for Al3+ with no significant distortion of the coordination tetrahedron in natrolite. Comparison of data for several natural and synthetic crystals reveals that the 4-rank zero-field splitting tensor invariants for Fe3+ at the tetrahedral oxygen-coordinated sites are distinguishably smaller than those for Fe3+ at octahedral sites. Such comparative analysis may help to determine the substitutional sites in other crystals.
Xingqiang Shi - One of the best experts on this subject based on the ideXlab platform.
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influences of Spin orbit coupling on fermi surfaces and dirac cones in ferroelectriclike polar metals
Physical Review B, 2019Co-Authors: Hu Zhang, Wei Huang, Jia-wei Mei, Xingqiang ShiAbstract:Based on first-principles calculations and $k\ifmmode\cdot\else\textperiodcentered\fi{}p$ effective models, we report physical properties of ferroelectriclike hexagonal polar metals with $P{6}_{3}mc$ Symmetry, which are distinct from those of conventional metals with spatial inversion Symmetry. Spin textures exist on the Fermi surface of polar metals (e.g., ternary LiGaGe and elemental polar metal of Bi) and Spin-momentum locking exist on accidental Dirac cones on the sixfold rotational axis, due to the Spin-orbit coupling and lack of inversion Symmetry in polar space group. This effect has potential applications in Spin-orbitronics. Dirac points are also predicted in LiGaGe.
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Influences of Spin-orbit coupling on Fermi surfaces and Dirac cones in ferroelectric-like polar metals.
arXiv: Materials Science, 2019Co-Authors: Hu Zhang, Wei Huang, Jia-wei Mei, Xingqiang ShiAbstract:Based on first-principles calculations and k .p effective models, we report physical properties of ferroelectric-like hexagonal polar metals with P63mc Symmetry, which are distinct from those of conventional metals with spatial inversion Symmetry. Spin textures exist on the Fermi surface of polar metals (e.g. ternary LiGaGe and elemental polar metal of Bi) and Spin-momentum locking exist on accidental Dirac cones on the sixfold rotational axis, due to the Spin-orbit coupling and lack of inversion Symmetry in polar space group. This effect has potential applications in Spin-orbitronics. Dirac points are also predicted in LiGaGe.
V M Vinokurov - One of the best experts on this subject based on the ideXlab platform.
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low Symmetry Spin hamiltonian and crystal field tensors analysis fe3 in natrolite
Journal of Magnetic Resonance, 2002Co-Authors: V M Vinokurov, G R Bulka, N M Khasanova, N M Nizamutdinov, A A Galeev, Jessica May G. Gaite, Czeslaw RudowiczAbstract:Electron paramagnetic resonance study of a natural single crystal of natrolite was carried out at the frequency ν=36.772 GHz at room temperature. The angular dependence of the four Symmetry-related spectra of Fe3+ in the three crystallographic planes was fitted to a Spin Hamiltonian (S=5/2) of Symmetry Ci. The rank 4 crystal field tensors at tetrahedral sites were calculated using the point-charge model to determine the principal axes orientations of their cubic and trigonal components. The analysis of zero-field splitting tensors and comparison with crystal field ones suggests that Fe3+ substitutes for Al3+ with no significant distortion of the coordination tetrahedron in natrolite. Comparison of data for several natural and synthetic crystals reveals that the 4-rank zero-field splitting tensor invariants for Fe3+ at the tetrahedral oxygen-coordinated sites are distinguishably smaller than those for Fe3+ at octahedral sites. Such comparative analysis may help to determine the substitutional sites in other crystals.
