Exotic vs. conventional scaling and universality in a disordered bilayer quantum Heisenberg antiferromagnet

TL;DR

This study uses large-scale Monte Carlo simulations to analyze a disordered bilayer quantum Heisenberg antiferromagnet, revealing a universal quantum phase transition characterized by finite-disorder fixed point and power-law scaling, contrasting with exotic scenarios in similar systems.

Contribution

It demonstrates that the quantum phase transition in a disordered bilayer Heisenberg antiferromagnet exhibits universal critical exponents and finite-disorder fixed point, challenging previous expectations of exotic scaling.

Findings

Critical exponents z=1.310(6) and ν=1.16(3) are universal and disorder-independent.

The transition is characterized by a finite-disorder fixed point with power-law scaling.

Strong corrections to scaling are accounted for with an irrelevant exponent ω=0.48.

Abstract

We present large-scale Monte-Carlo simulations of a two-dimensional (2d) bilayer quantum Heisenberg antiferromagnet with random dimer dilution. In contrast to the exotic scaling scenarios found in many other random quantum systems, the quantum phase transition in this system is characterized by a finite-disorder fixed point with power-law scaling. After accounting for strong corrections to scaling, characterized by a leading irrelevant exponent of \omega = 0.48, we find universal, i.e., disorder-independent, critical exponents z=1.310(6) and \nu=1.16(3). We discuss the consequences of these findings and suggest new experiments.