Critical Phenomena at the Antiferromagnetic Phase Transition of Azurite

摘要

We report on high-resolution acoustic, specific-heat and thermal expansionmeasurements 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. Adetailed investigation of the critical contribution to the various quantitiesat T_N is presented. The set of critical exponents and amplitude ratios of thesingular contributions above and below the transition indicate that the systemcan be reasonably well described by a three-dimensional Heisenbergantiferromagnet.