Multi-critical point in a diluted bilayer Heisenberg quantum antiferromagnet

TL;DR

This study uses quantum Monte Carlo simulations to identify a multi-critical point in a diluted bilayer Heisenberg antiferromagnet, revealing critical behavior at the intersection of percolation and quantum phase transitions.

Contribution

It demonstrates the existence of a zero-temperature multi-critical point at specific dilution and coupling, with determined quantum critical exponents, extending understanding of quantum criticality in disordered antiferromagnets.

Findings

Identification of a multi-critical point at p* and g* approximately 0.16.

Determination of quantum critical exponents via finite-size scaling.

Finite-temperature quantum critical regime extends to zero inter-layer coupling.

Abstract

The S=1/2 Heisenberg bilayer antiferromagnet with randomly removed inter-layer dimers is studied using quantum Monte Carlo simulations. A zero-temperature multi-critical point (p*,g*) at the classical percolation density p=p* and inter-layer coupling g* approximately 0.16 is demonstrated. The quantum critical exponents of the percolating cluster are determined using finite-size scaling. It is argued that the associated finite-temperature quantum critical regime extends to zero inter-layer coupling and could be relevant for antiferromagnetic cuprates doped with non-magnetic impurities.