Ground state and low-energy excitations of the Kitaev-Heisenberg two-leg ladder

  title={Ground state and low-energy excitations of the Kitaev-Heisenberg two-leg ladder},
  author={Cli{\`o} Efthimia Agrapidis and Jeroen van den Brink and Satoshi Nishimoto},
  journal={Physical Review B},
We study the ground state and low-lying excited states of the Kitaev-Heisenberg model on a ladder geometry using the density matrix renormalization group and Lanczos exact diagonalization methods. The Kitaev and Heisenberg interactions are parametrized as $K=\sin\phi$ and $J=\cos\phi$ with an angle parameter $\phi$. Based on the results for several types of order parameters, excitation gaps, and entanglement spectra, the $\phi$-dependent ground-state phase diagram is determined. Remarkably, the… 

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