Critical Phenomena at the Antiferromagnetic Phase Transition of Azurite

TL;DR

This study investigates the critical behavior of azurite at its antiferromagnetic transition, revealing it behaves like a three-dimensional Heisenberg antiferromagnet through detailed measurements of thermodynamic quantities.

Contribution

It provides the first detailed critical exponent analysis of azurite's antiferromagnetic transition, confirming its classification as a 3D Heisenberg antiferromagnet.

Findings

Critical exponents consistent with 3D Heisenberg universality class

Quantitative analysis of amplitude ratios above and below T_N

High-resolution measurements of thermodynamic quantities near T_N

Abstract

We report on high-resolution acoustic, specific-heat and thermal expansion measurements in the vicinity of the antiferromagnetic phase transition at T_N = 1.88 K on a high-quality single crystal of the natural mineral azurite. A detailed investigation of the critical contribution to the various quantities at T_N is presented. The set of critical exponents and amplitude ratios of the singular contributions above and below the transition indicate that the system can be reasonably well described by a three-dimensional Heisenberg antiferromagnet.