Unveiling the phase diagram of a bond-alternating spin-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mfrac><mml:mn>1</mml:mn><mml:mn>2</mml:mn></mml:mfrac></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>K</mml:mi><mml:mtext>−</mml:mtext><mml:mi mathvariant="normal">Γ</mml:mi></mml:mrow></mml:math> chain

Abstract

The quantum spin chain with bond-directional interactions can host fascinating phenomena. Here, the authors study such a spin chain, built of a Kitaev interaction and an off-diagonal exchange (dubbed the $\mathrm{\ensuremath{\Gamma}}$ term). This model possesses a self-dual relation and a mirror symmetry, and is found to exhibit a multicritical point, two topological phase transitions of distinct universality classes, three magnetically ordered states, and four disordered phases including the preeminent Haldane phase. These findings demonstrate a fertile playground to study quantum magnetism and topological phase transitions.

Topics & Concepts