The Experts below are selected from a list of 53568 Experts worldwide ranked by ideXlab platform
Yong Baek Kim - One of the best experts on this subject based on the ideXlab platform.
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Signatures of spin-triplet excitations in Optical Conductivity of valence bond solids
New Journal of Physics, 2014Co-Authors: Kyusung Hwang, Subhro Bhattacharjee, Yong Baek KimAbstract:We show that the Optical responses below the Mott gap can be used to probe the spin-triplet excitations in valence bond solid (VBS) phases in Mott insulators. The Optical Conductivity in this regime arises due to the electronic polarization mechanism via virtual electron hopping processes. We apply this mechanism to the Hubbard model with spin-orbit couplings and/or the corresponding spin model with significant Dzyaloshinskii-Moriya (DM) interactions, and compute the Optical Conductivity of VBS states on both ideal and deformed Kagome lattices. In case of the deformed Kagome lattice, we study the antiferromagnet, Rb$_2$Cu$_3$SnF$_{12}$ with the pinwheel VBS state. In case of the ideal Kagome lattice, we explore the Optical Conductivity signatures of the spin-triplet excitations for three VBS states with (1) a 12-site unit cell, (2) a 36-site unit cell with six-fold rotation symmetry, and (3) a 36-site unit cell with three-fold rotation symmetry, respectively. We find that increasing the DM interactions generally leads to broad and smooth features in the Optical Conductivity with interesting experimental consequences. The Optical Conductivity reflects the features of the spin-triplet excitations that can be measured in future experiments.
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signatures of spin triplet excitations in Optical Conductivity of valence bond solids
New Journal of Physics, 2014Co-Authors: Kyusung Hwang, Subhro Bhattacharjee, Yong Baek KimAbstract:We show that the Optical responses below the Mott gap can be used to probe the spin-triplet excitations in valence bond solid (VBS) phases in Mott insulators. The Optical Conductivity in this regime arises due to the electronic polarization mechanism via virtual electron-hopping processes. We apply this mechanism to the Hubbard model with spin–orbit couplings and/or the corresponding spin model with significant Dzyaloshinskii–Moriya (DM) interactions, and compute the Optical Conductivity of VBS states on both ideal and deformed Kagome lattices. In the case of the deformed Kagome lattice, we study the antiferromagnet Rb2Cu3SnF12 with the pinwheel VBS state. In case of the ideal Kagome lattice, we explore the Optical Conductivity signatures of the spin-triplet excitations for three VBS states with (1) a 12-site unit cell, (2) a 36-site unit cell with six-fold rotation symmetry, and (3) a 36-site unit cell with three-fold rotation symmetry, respectively. We find that increasing the DM interactions generally leads to broad and smooth features in the Optical Conductivity with interesting experimental consequences. The Optical Conductivity reflects the features of the spin-triplet excitations that can be measured in future experiments.
Kyusung Hwang - One of the best experts on this subject based on the ideXlab platform.
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Signatures of spin-triplet excitations in Optical Conductivity of valence bond solids
New Journal of Physics, 2014Co-Authors: Kyusung Hwang, Subhro Bhattacharjee, Yong Baek KimAbstract:We show that the Optical responses below the Mott gap can be used to probe the spin-triplet excitations in valence bond solid (VBS) phases in Mott insulators. The Optical Conductivity in this regime arises due to the electronic polarization mechanism via virtual electron hopping processes. We apply this mechanism to the Hubbard model with spin-orbit couplings and/or the corresponding spin model with significant Dzyaloshinskii-Moriya (DM) interactions, and compute the Optical Conductivity of VBS states on both ideal and deformed Kagome lattices. In case of the deformed Kagome lattice, we study the antiferromagnet, Rb$_2$Cu$_3$SnF$_{12}$ with the pinwheel VBS state. In case of the ideal Kagome lattice, we explore the Optical Conductivity signatures of the spin-triplet excitations for three VBS states with (1) a 12-site unit cell, (2) a 36-site unit cell with six-fold rotation symmetry, and (3) a 36-site unit cell with three-fold rotation symmetry, respectively. We find that increasing the DM interactions generally leads to broad and smooth features in the Optical Conductivity with interesting experimental consequences. The Optical Conductivity reflects the features of the spin-triplet excitations that can be measured in future experiments.
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signatures of spin triplet excitations in Optical Conductivity of valence bond solids
New Journal of Physics, 2014Co-Authors: Kyusung Hwang, Subhro Bhattacharjee, Yong Baek KimAbstract:We show that the Optical responses below the Mott gap can be used to probe the spin-triplet excitations in valence bond solid (VBS) phases in Mott insulators. The Optical Conductivity in this regime arises due to the electronic polarization mechanism via virtual electron-hopping processes. We apply this mechanism to the Hubbard model with spin–orbit couplings and/or the corresponding spin model with significant Dzyaloshinskii–Moriya (DM) interactions, and compute the Optical Conductivity of VBS states on both ideal and deformed Kagome lattices. In the case of the deformed Kagome lattice, we study the antiferromagnet Rb2Cu3SnF12 with the pinwheel VBS state. In case of the ideal Kagome lattice, we explore the Optical Conductivity signatures of the spin-triplet excitations for three VBS states with (1) a 12-site unit cell, (2) a 36-site unit cell with six-fold rotation symmetry, and (3) a 36-site unit cell with three-fold rotation symmetry, respectively. We find that increasing the DM interactions generally leads to broad and smooth features in the Optical Conductivity with interesting experimental consequences. The Optical Conductivity reflects the features of the spin-triplet excitations that can be measured in future experiments.
Renato Pucci - One of the best experts on this subject based on the ideXlab platform.
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Strain effect on the Optical Conductivity of graphene
Physical Review B, 2010Co-Authors: F. M.d. Pellegrino, G. G. N. Angilella, Renato PucciAbstract:Within the tight binding approximation, we study the dependence of the electronic band structure and of the Optical Conductivity of a graphene single layer on the modulus and direction of applied uniaxial strain. While the Dirac cone approximation, albeit with a deformed cone, is robust for sufficiently small strain, band dispersion linearity breaks down along a given direction, corresponding to the development of anisotropic massive low-energy excitations. We recover a linear behavior of the low-energy density of states, as long as the cone approximation holds, while a band gap opens for sufficiently intense strain, for almost all, generic strain directions. This may be interpreted in terms of an electronic topological transition, corresponding to a change of topology of the Fermi line, and to the merging of two inequivalent Dirac points as a function of strain. We propose that these features may be observed in the frequency dependence of the longitudinal Optical Conductivity in the visible range, as a function of strain modulus and direction, as well as of field orientation.Comment: Phys. Rev. B, to appea
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Strain effect on the Optical Conductivity of graphene
Physical Review B, 2010Co-Authors: F. M.d. Pellegrino, G. G. N. Angilella, Renato PucciAbstract:Within the tight binding approximation, we study the dependence of the electronic band structure and of the Optical Conductivity of a graphene single layer on the modulus and direction of applied uniaxial strain. While the Dirac cone approximation, albeit with a deformed cone, is robust for sufficiently small strain, band dispersion linearity breaks down along a given direction, corresponding to the development of anisotropic massive low-energy excitations. We recover a linear behavior of the low-energy density of states, as long as the cone approximation holds, while a band gap opens for sufficiently intense strain, for almost all, generic strain directions. This may be interpreted in terms of an electronic topological transition, corresponding to a change of topology of the Fermi line, and to the merging of two inequivalent Dirac points as a function of strain. We propose that these features may be observed in the frequency dependence of the longitudinal Optical Conductivity in the visible range, as a function of strain modulus and direction, as well as of field orientation.
Patrick A Lee - One of the best experts on this subject based on the ideXlab platform.
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Optical Conductivity from pair density waves
Physical Review B, 2017Co-Authors: Zhehao Dai, Patrick A LeeAbstract:We present a theory of Optical Conductivity in systems with finite-momentum Cooper pairs. In contrast to the BCS pairing where AC Conductivity is purely imaginary in the clean limit, there is nonzero AC absorption across the superconducting gap for finite-momentum pairing if we break the Galilean symmetry explicitly in the electronic Hamiltonian. Vertex correction is crucial for maintaining the gauge invariance in the mean-field formalism and dramatically changes the Optical Conductivity in the direction of the pairing momentum. We carried out a self-consistent calculation and gave an explicit formula for Optical Conductivity in a simple case. This result applies to the Fulde-Ferrell-Larkin-Ovchinnikov state and candidates with pair density waves proposed for High- Tc cuprates. It may help detect PDW and determine the pairing gap as well as the direction of the pairing momentum in experiments.
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Optical Conductivity from pair density waves
Physical Review B, 2017Co-Authors: Zhehao Dai, Patrick A LeeAbstract:We present a theory of Optical Conductivity in systems with finite-momentum Cooper pairs. In contrast to the BCS pairing where ac Conductivity is purely imaginary in the clean limit, there is nonzero ac absorption across the superconducting gap for finite-momentum pairing if we break the Galilean symmetry explicitly in the electronic Hamiltonian. Vertex correction is crucial for maintaining the gauge invariance in the mean-field formalism and dramatically changes the Optical Conductivity in the direction of the pairing momentum. We carried out a self-consistent calculation and gave an explicit formula for Optical Conductivity in a simple case. This result applies to the Fulde-Ferrell-Larkin-Ovchinnikov state and candidates with pair density waves proposed for high-T_{c} cuprates. It may help detect pair density waves and determine the pairing gap as well as the direction of the pairing momentum in experiments.National Science Foundation (U.S.) (Grant DMR-1522575
Subhro Bhattacharjee - One of the best experts on this subject based on the ideXlab platform.
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Signatures of spin-triplet excitations in Optical Conductivity of valence bond solids
New Journal of Physics, 2014Co-Authors: Kyusung Hwang, Subhro Bhattacharjee, Yong Baek KimAbstract:We show that the Optical responses below the Mott gap can be used to probe the spin-triplet excitations in valence bond solid (VBS) phases in Mott insulators. The Optical Conductivity in this regime arises due to the electronic polarization mechanism via virtual electron hopping processes. We apply this mechanism to the Hubbard model with spin-orbit couplings and/or the corresponding spin model with significant Dzyaloshinskii-Moriya (DM) interactions, and compute the Optical Conductivity of VBS states on both ideal and deformed Kagome lattices. In case of the deformed Kagome lattice, we study the antiferromagnet, Rb$_2$Cu$_3$SnF$_{12}$ with the pinwheel VBS state. In case of the ideal Kagome lattice, we explore the Optical Conductivity signatures of the spin-triplet excitations for three VBS states with (1) a 12-site unit cell, (2) a 36-site unit cell with six-fold rotation symmetry, and (3) a 36-site unit cell with three-fold rotation symmetry, respectively. We find that increasing the DM interactions generally leads to broad and smooth features in the Optical Conductivity with interesting experimental consequences. The Optical Conductivity reflects the features of the spin-triplet excitations that can be measured in future experiments.
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signatures of spin triplet excitations in Optical Conductivity of valence bond solids
New Journal of Physics, 2014Co-Authors: Kyusung Hwang, Subhro Bhattacharjee, Yong Baek KimAbstract:We show that the Optical responses below the Mott gap can be used to probe the spin-triplet excitations in valence bond solid (VBS) phases in Mott insulators. The Optical Conductivity in this regime arises due to the electronic polarization mechanism via virtual electron-hopping processes. We apply this mechanism to the Hubbard model with spin–orbit couplings and/or the corresponding spin model with significant Dzyaloshinskii–Moriya (DM) interactions, and compute the Optical Conductivity of VBS states on both ideal and deformed Kagome lattices. In the case of the deformed Kagome lattice, we study the antiferromagnet Rb2Cu3SnF12 with the pinwheel VBS state. In case of the ideal Kagome lattice, we explore the Optical Conductivity signatures of the spin-triplet excitations for three VBS states with (1) a 12-site unit cell, (2) a 36-site unit cell with six-fold rotation symmetry, and (3) a 36-site unit cell with three-fold rotation symmetry, respectively. We find that increasing the DM interactions generally leads to broad and smooth features in the Optical Conductivity with interesting experimental consequences. The Optical Conductivity reflects the features of the spin-triplet excitations that can be measured in future experiments.