Variational study of the Kitaev-Heisenberg-Gamma model

Shang Shun Zhang, Gábor B. Halász, Wei Zhu, Cristian D. Batista

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Abstract

We compute the low-energy excitation spectrum and the dynamical spin structure factor of the Kitaev-Heisenberg-Gamma model through a variational approach based on the exact fractionalized excitations of the pure Kitaev honeycomb model. This novel approach reveals the physical reason for the asymmetric stability of the Kitaev spin liquid phases around the ferromagnetic and antiferromagnetic Kitaev limits. Moreover, we demonstrate that the fractionalized excitations form bound states in specific regions of each Kitaev spin liquid phase and that certain phase transitions induced by Heisenberg and Gamma interactions are driven by the condensation of such a bound state. Remarkably, this bound state appears as a sharp mode in the dynamical spin structure factor, while its condensation patterns at the appropriate phase transitions provide a simple explanation for the magnetically ordered phases surrounding each Kitaev spin liquid phase.

Original languageEnglish
Article number014411
JournalPhysical Review B
Volume104
Issue number1
DOIs
StatePublished - Jul 1 2021

Funding

S.-S.Z. and C.D.B. are supported by funding from the Lincoln Chair of Excellence in Physics and from the Los Alamos National Laboratory Directed Research and Development program. W.Z. is supported by the Key R&D Program of Zhejiang Province, China (2021C01002). G.B.H. was supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Science Center.

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