Disorder Induced Phase Transition in a Random Quantum Antiferromagnet

TL;DR

This paper investigates how increasing randomness in a 2D quantum antiferromagnet causes a phase transition from an ordered to a disordered state, using quantum Monte Carlo simulations.

Contribution

It demonstrates a disorder-induced phase transition in a 2D quantum antiferromagnet and characterizes the critical behavior with finite-size scaling.

Findings

Transition from ordered to disordered state with increased randomness

Dynamic exponent z = 2 at the transition

Finite-size scaling supports the critical behavior

Abstract

A two-dimensional Heisenberg model with random antiferromagnetic nearest-neighbor exchange is studied using quantum Monte Carlo techniques. As the strength of the randomness is increased, the system undergoes a transition from an antiferromagnetically ordered ground state to a gapless disordered state. The finite-size scaling of the staggered structure factor and susceptibility is consistent with a dynamic exponent $z = 2$.