Exact diagonalization studies of an effective model for
quantum kagome ice Kai-Hsin Wu ^{1,3*}, Yi-Ping Huang^{2}, Ying-Jer Kao^{1,3,4}^{1}Department of Physics, National Taiwan University, Taipei, Taiwan^{2}Max Planck Institute for the Physics of Complex Systems, Dresden, Germany^{3}National Center for Theoretical Sciences, National Tsing Hua University, Hsinchu, Taiwan^{4}Department 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 results. [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 |