%0 Journal Article %1 PhysRevB.99.224418 %A Agrapidis, Cliò Efthimia %A van den Brink, Jeroen %A Nishimoto, Satoshi %D 2019 %I American Physical Society %J Phys. Rev. B %K a b %N 22 %P 224418 %R 10.1103/PhysRevB.99.224418 %T Ground state and low-energy excitations of the Kitaev-Heisenberg two-leg ladder %U https://link.aps.org/doi/10.1103/PhysRevB.99.224418 %V 99 %X We study the ground state and low-lying excited states of the Kitaev-Heisenberg model on a two-leg ladder geometry using the density-matrix renormalization-group and Lanczos exact diagonalization methods. The Kitaev and Heisenberg interactions are parametrized as K=sinϕ and J=cosϕ with an angle parameter ϕ. Based on the results for several types of order parameters, excitation gaps, string order parameter, and entanglement spectra, the ϕ-dependent ground state phase diagram is determined. Remarkably, the phase diagram is quite similar to that of the Kitaev-Heisenberg model on a honeycomb lattice, exhibiting the same long-range-ordered states, namely rung singlet (analog to Néel in three dimensions), zigzag, ferromagnetic, and stripy, and the presence of gapped spin liquids around the exactly solvable Kitaev points ϕ=±π/2. We also calculate the expectation value of a plaquette operator corresponding to a π-flux state in order to establish how the gapped Kitaev spin liquid extends away from the ϕ=±π/2. Furthermore, we determine the dynamical spin structure factor and discuss the effect of the Kitaev interaction on the spin-triplet dispersion.

@article{PhysRevB.99.224418, abstract = {We study the ground state and low-lying excited states of the Kitaev-Heisenberg model on a two-leg ladder geometry using the density-matrix renormalization-group and Lanczos exact diagonalization methods. The Kitaev and Heisenberg interactions are parametrized as K=sinϕ and J=cosϕ with an angle parameter ϕ. Based on the results for several types of order parameters, excitation gaps, string order parameter, and entanglement spectra, the ϕ-dependent ground state phase diagram is determined. Remarkably, the phase diagram is quite similar to that of the Kitaev-Heisenberg model on a honeycomb lattice, exhibiting the same long-range-ordered states, namely rung singlet (analog to Néel in three dimensions), zigzag, ferromagnetic, and stripy, and the presence of gapped spin liquids around the exactly solvable Kitaev points ϕ=±π/2. We also calculate the expectation value of a plaquette operator corresponding to a π-flux state in order to establish how the gapped Kitaev spin liquid extends away from the ϕ=±π/2. Furthermore, we determine the dynamical spin structure factor and discuss the effect of the Kitaev interaction on the spin-triplet dispersion.}, added-at = {2019-08-19T09:37:13.000+0200}, author = {Agrapidis, Cliò Efthimia and van den Brink, Jeroen and Nishimoto, Satoshi}, biburl = {https://www.bibsonomy.org/bibtex/27fbc7865d5bffd74973639ea544c3cd6/ctqmat}, day = 13, description = {Phys. Rev. B 99, 224418 (2019) - Ground state and low-energy excitations of the Kitaev-Heisenberg two-leg ladder}, doi = {10.1103/PhysRevB.99.224418}, interhash = {d3e7d50acdd0d6c08e3d45e7a691c542}, intrahash = {7fbc7865d5bffd74973639ea544c3cd6}, journal = {Phys. Rev. B}, keywords = {a b}, month = {06}, number = 22, numpages = {11}, pages = 224418, publisher = {American Physical Society}, timestamp = {2023-01-16T14:49:29.000+0100}, title = {Ground state and low-energy excitations of the Kitaev-Heisenberg two-leg ladder}, url = {https://link.aps.org/doi/10.1103/PhysRevB.99.224418}, volume = 99, year = 2019 }