Exact diagonalization studies of an effective model for quantum kagome ice
Kai-Hsin Wu1,3*, Yi-Ping Huang2, Ying-Jer Kao1,3,4
1Department of Physics, National Taiwan University, Taipei, Taiwan
2Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
3National Center for Theoretical Sciences, National Tsing Hua University, Hsinchu, Taiwan
4Department of Physics, Boston University, Massachusetts, USA
* Presenter:Kai-Hsin Wu, email:kaihsinwu@gmail.com
We study the spin-1/2 kagome Heisenberg XYZh model in the so-called quantum kagome
ice regime[1]. From our recent topological entanglement entropy and thermal entropy studies,
we find that the system does not show a Z2 topological order down to β = 48, while the
thermal entropy down to β = 200 is consistent with the residual entropy of a classical kagome
ice in a magnetic field [2]. Using degenerate perturbation theory (DPT) out of the classical
ice manifold, we derive an effective model which shows an intricate competition between the
ring-exchange and diagonal processes. Here, we perform exact diagonalization on the effective
Hamiltonian. By tuning the weight of the diagonal term, we find that the competition can lead
to a quasi-degenerate energy spectrum, consistent with the Quantum Monte Carlo simulation

[1] J. Carrasquilla, Z. Hao and R. G. Melko Nature communications 6 (2015)
[2] K.-H. Wu, Y.-P. Huang and Y.-J. Kao arXiv:1806.08145

Keywords: Quantum kagome ice, XYZh model , Quantum Monte-Carlo , Exact diagonalization