Quantum criticality in a three dimensional spin system at zero field and pressure

TL;DR

This paper investigates quantum criticality in a 3D spin system, revealing a magnetic quantum critical point with unusual critical exponents induced by bromine concentration changes.

Contribution

It demonstrates the emergence of antiferromagnetic order in a gapped quantum paramagnet and characterizes its unconventional quantum critical behavior.

Findings

Antiferromagnetic order appears at a critical bromine concentration.

The critical scaling shows unusual critical exponents.

The transition resembles a z=1 magnetic quantum critical point.

Abstract

We report spontaneous appearance of antiferromagnetic order in a model gapped quantum paramagnet Ni(Cl$_{1-x}$Br$_x$)$_2$$\cdot$4SC(NH$_2$)$_2$ induced by a change in bromine concentration x. This transition is qualitatively similar to a z = 1 magnetic quantum critical point. However, the observed critical scaling of thermodynamic and magnetic properties has rather unusual critical exponents.