Three Dimensional XY Critical Behavior of Heat Capacity at Normal-Incommensurate Phase Transition in Rb₂ZnCl₄

抄録

A high-resolution heat capacity measurement has been carried out near the normal-incommensurate phase transition in Rb₂ZnCl₄ by an ac calorimeter. The obtained data have been analyzed with a renormalization-group expression which includes correction terms up to the second order. It was found that the heat capacity anomaly is described well with the three dimensional XY model; the critical exponent, the critical amplitude ratio, and the universal constant derived from the first-order correction amplitude agree well with the theoretically expected values.