Z $_{\mathrm{2}}$ gauge theory for valence bond solids on the kagome latticeZ$_{\mathrm{2}}$ gauge theory for valence bond solids on the kagome lattice

Kyusung Hwang, Yejin Huh, Yong Baek Kim

Bulletin of the American Physical SocietyMar 18, 20160 citations

Valence Bond States on the kagome lattice: Linear Independence and RVB-Hamiltonian

Alexander Seidel

Bulletin of the American Physical SocietyMar 16, 20100 citations

Signatures of spin-triplet excitations in optical conductivity of valence bond solids

Kyusung Hwang, Subhro Bhattacharjee, Yong Baek Kim

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.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.

arXiv:1311.5569New Journal of PhysicsDec 2, 20147 citations

Optical conductivity of visons in Z2 spin liquids close to a valence bond solid transition on the kagome lattice

Yejin Huh, Matthias Punk, Subir Sachdev A

We consider ${Z}_{2}$ spin liquids on the kagome lattice on the verge of a valence bond solid (VBS) transition, where vortex excitations carrying ${Z}_{2}$ magnetic flux---so-called visons---condense. We show that these vison excitations can couple directly to the external electromagnetic field, even though they carry neither spin nor charge. This is possible via a magnetoelastic coupling mechanism recently identified. [Potter, Senthil, and Lee, arXiv:1301.3495; Hao, Phys. Rev. B 85, 174432 (2012)] For the case of transitions to a 36-site unit cell VBS state, the corresponding finite ac conductivity has a specific power-law frequency dependence, which is related to the crossover exponent of the quantum critical point. The visons' contribution to the optical conductivity at transitions to VBS states with a 12-site unit cell vanishes, however.We consider ${Z}_{2}$ spin liquids on the kagome lattice on the verge of a valence bond solid (VBS) transition, where vortex excitations carrying ${Z}_{2}$ magnetic flux---so-called visons---condense. We show that these vison excitations can couple directly to the external electromagnetic field, even though they carry neither spin nor charge. This is possible via a magnetoelastic coupling mechanism recently identified. [Potter, Senthil, and Lee, arXiv:1301.3495; Hao, Phys. Rev. B 85, 174432 (2012)] For the case of transitions to a 36-site unit cell VBS state, the corresponding finite ac conductivity has a specific power-law frequency dependence, which is related to the crossover exponent of the quantum critical point. The visons' contribution to the optical conductivity at transitions to VBS states with a 12-site unit cell vanishes, however.

arXiv:1303.7235Physical Review BJun 10, 201312 citations

Topological Phases of Fermions in Kagome Optical Lattices

V. W. Scarola, Mengsu Chen, Hoi-Yin Hui +1 more

Bulletin of the American Physical SocietyMar 7, 20190 citations

_{\mathrm{2}}

gauge theory for valence bond solids on the kagome lattice

_2

_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.

We consider

{Z}_{2}

spin liquids on the kagome lattice on the verge of a valence bond solid (VBS) transition, where vortex excitations carrying

{Z}_{2}

magnetic flux---so-called visons---condense. We show that these vison excitations can couple directly to the external electromagnetic field, even though they carry neither spin nor charge. This is possible via a magnetoelastic coupling mechanism recently identified. [Potter, Senthil, and Lee, arXiv:1301.3495; Hao, Phys. Rev. B 85, 174432 (2012)] For the case of transitions to a 36-site unit cell VBS state, the corresponding finite ac conductivity has a specific power-law frequency dependence, which is related to the crossover exponent of the quantum critical point. The visons' contribution to the optical conductivity at transitions to VBS states with a 12-site unit cell vanishes, however.