Title: Coupled-chain analysis of Kitaev materials

Speaker: Wang Yang (School of Physics, Nankai University)

Time: 14:00 pm, May 15th，2024

Venue: C302, New Science Building

Abstract: Kitaev spin-1/2 materials on the honeycomb lattice are a class of candidate materials that can potentially be used for realizing topological quantum computations. Existing Kitaev materials exhibit magnetic orders at low temperatures, including zigzag, counter-rotating spiral, and triple-Q orders, among others. In this talk, I will discuss our recent progress in understanding the magnetic orders in Kitaev materials using a coupled-chain analysis. In the first part of the talk, I will start with a single spin-1/2 Kitaev-Gamma chain and show that an extended gapless phase with an emergent SU(2)1 symmetry exists. Using this as a perturbative starting point, we studied the Kitaev-Heisenberg-Gamma chain and found a gapless phase and a ferromagnetic phase. In the second part, I will describe how we extended these 1D findings to 2D by connecting 1D chains together and treating the interchain interactions in a self-consistent mean field approach. The coupled-chain method successfully explains the zigzag order in alpha-RuCl3 and Na2IrO3, as well as the counter-rotating spiral order in alpha-Li2IrO3, based on the nearest-neighboring Kitaev-Heisenberg-Gamma model without requiring more complex interactions. In addition, a quantum critical point at (K=-1.68Γ<0, J>0) is found where five different magnetically ordered phases meet.

Ref:

[1] W. Yang, A. Nocera, T. Tummuru, H.-Y. Kee, I. Affleck, Phys. Rev. Lett. 124, 147205 (2020).

[2] W. Yang, A. Nocera, I. Affleck, Phys. Rev. Research 2, 033268 (2020).

[3] W. Yang, A. Nocera, C. Xu, H.-Y. Kee, I. Affleck, arXiv:2207.02188 (2022)