Interplay of Kitaev Interaction and Off-diagonal Exchanges: Exotic Phases and Quantum Phase Diagrams

TL;DR

This paper reviews how the competition between Kitaev interactions and off-diagonal exchanges leads to exotic quantum phases and complex phase diagrams in Kitaev magnets, highlighting the role of numerical studies.

Contribution

It provides a comprehensive numerical analysis of the interplay between Kitaev and off-diagonal exchanges, revealing new exotic phases and detailed quantum phase diagrams.

Findings

Identification of $ ext{Γ}$ spin liquid and nematic ferromagnet phases.

Discovery of chiral-spin states with broken time-reversal symmetry.

Complex phase diagrams with multiple ordered and disordered phases.

Abstract

Aligning with the everlasting search for quantum spin liquids (QSLs), identifying the QSL in Kitaev magnets has garnered great research interest during the past decade and remains nevertheless an enormous challenge. One of the major difficulties lies in that Kitaev QSL is typically fragile against competing interactions like off-diagonal exchanges, which are ubiquitous in real materials due to spin-orbit coupling and crystal-field effect. This, in turn, gives rise to many intriguing field-induced novel phases and thermal Hall effect. In this review, we will focus on the interplay of Kitaev interaction and off-diagonal $\Gamma$ and $\Gamma'$ exchanges from a numerical perspective. This review discusses some representative exotic phases such as $\Gamma$ spin liquid, nematic ferromagnet, spin-flop phase, and distinct chiral-spin states with spontaneously time-reversal symmetry breaking. It also presents quantum phase diagrams of anisotropic Kitaev-$\Gamma$ chains that exhibit kaleidoscopes of both ordered and disordered phases.