Quantum phase transitions in spin-1 compass chains

TL;DR

This paper investigates quantum phase transitions in a spin-1 compass chain using iTEBD, identifying various phases, their order, and critical properties, including the universality class and entanglement features.

Contribution

It introduces a generalized string correlator to describe nonlocal order and characterizes the nature and universality of phase transitions in the model.

Findings

Identification of multiple phases via energy, spin correlations, and entanglement entropy

Discovery of a generalized string correlator for nonlocal order

Critical points exhibit Ising universality with central charge c=1/2

Abstract

The ground-state phase diagram and quantum phase transitions (QPTs) in a spin-1 compass chain are investigated by the infinite time-evolving block decimation (iTEBD) method. Various phases are discerned by energy densities, spin correlations and entanglement entropy. A generalized string correlator is found to be capable of describing the nonlocal string order in the disordered phase. Furthermore, in the noncritical disordered phase, the spin-spin correlations are found to decay exponentially. Except for a multicritical point ($J_{1}=0$, $J_{2}=0$), the QPTs are determined to have second-order characters. In addition, the central charges on these critical phase boundaries are determined to be $c$=1/2, therefore these QPTs belong to the Ising universality class.