Magnetization plateau and quantum phase transitions in a spin-orbital model

TL;DR

This paper investigates a spin-orbital chain with anisotropy and different Landé g-factors, revealing magnetization plateaus and multiple quantum phase transitions through analytical and numerical methods.

Contribution

It provides a detailed phase diagram and explicit analytical expressions for critical fields in a spin-orbital model with anisotropy and Landé g-factor differences.

Findings

Existence of magnetization plateau due to Landé g-factor differences

Identification of five quantum phase transitions under varying magnetic field

Analytical expressions for critical fields in the SU(4) model

Abstract

A spin-orbital chain with different Land\'e $g$ factors and one-ion anisotropy is studied in the context of the thermodynamical Bethe ansatz. It is found that there exists a magnetization plateau resulting from the different Land\'e $g$ factors. Detailed phase diagram in the presence of an external magnetic field is presented both numerically and analytically. For some values of the anisotropy, the four-component system undergoes five consecutive quantum phase transitions when the magnetic field varies. We also study the magnetization in various cases, especially its behaviors in the vicinity of the critical points. For the SU(4) spin-orbital model, explicit analytical expressions for the critical fields are derived, with excellent accuracy compared with numerics.