1D valence bond solids in a magnetic field

TL;DR

This paper investigates the phase transition between valence bond solid and ferromagnetic states in a 1D quantum spin system under an external magnetic field, using advanced quantum Monte Carlo simulations.

Contribution

It provides the first detailed phase diagram of the 1D J-Q$_2$ model under magnetic field, highlighting the competition between VBS order and ferromagnetism.

Findings

Identification of phase boundaries between VBS and ferromagnetic states.

Demonstration of quantum phase transitions driven by magnetic field.

Insights into the stability of VBS order in one-dimensional systems.

Abstract

A Valence bond solid (VBS) is a nonmagnetic, long-range ordered state of a quantum spin system where local spin singlets are formed in some regular pattern. We here study the competition between VBS order and a fully polarized ferromagnetic state as function of an external magnetic field in a one-dimensional extended Heisenberg model---the J-Q$_2$ model---using stochastic series expansion quantum Monte Carlo simulations with directed loop updates. We discuss the ground state phase diagram.