Model for frustrated spin-orbital chains: application to CaV2O4

TL;DR

This paper investigates the complex ground states of a frustrated spin-orbital chain relevant to CaV2O4, revealing multiple phases, spin liquids, and the effects of spin-orbit coupling and Jahn-Teller interactions.

Contribution

It introduces a comprehensive model for CaV2O4's spin-orbital chain, analyzing phase transitions and spin liquid states influenced by spin-orbit and Jahn-Teller effects.

Findings

Identification of an antiferro-orbital phase separated by a continuous Ising transition.

Discovery of two distinct spin liquid states depending on orbital order.

Behavior of the chain as a spin-2 chain with Ising anisotropy in the strong spin-orbit limit.

Abstract

Motivated by recent interest in quasi-one-dimensional compound CaV2O4, we study the ground states of a spin-orbital chain characterized by an Ising-like orbital Hamiltonian and frustrated interactions between S=1 spins. The on-site spin-orbit interaction and Jahn-Teller effect compete with inter-site superexchange leading to a rich phase diagram in which an antiferro-orbital phase is separated from the orbital paramagnet by a continuous Ising transition. Two distinct spin liquids depending on the underlying orbital order are found in the limit of small spin-orbit coupling. In the opposite limit, the zigzag chain behaves as a spin-2 chain with Ising anisotropy. The implications for CaV2O4 are discussed.