Specific Heat of Stage-2 MnCl

概要

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Stage-2 MnCl<inf>2</inf>GIC magnetically behaves like a quasi 2D XY antiferromagnet on the triangular lattice with the spin freezing temperature T_{\text{SG}} (= 1.1 K). We have undertaken an extensive study on the T dependence of specific heat in the absence of an external field H and in the presence of H along the c-plane. The magnetic specific heat C_{\text{mag}} at H = 0 shows no anomaly at T_{\text{SG}}, but exhibits double broad peaks around 5 and 41 K. The anomaly at 41 K is the onset of short range spin correlation. The magnetic specific heat C_{\text{mag}} at H = 0 is described by C_{\text{mag}} \propto (1/T^{2})\exp(-\Delta/T) with \Delta = 1.41 \pm 0.03 K, while C_{\text{mag}} at H = 10 kOe is proportional to T. The entropy due to the broad peak around 5 K is 1/3 of the total entropy. The residual entropy is 63% of the total entropy because of highly frustrated nature of the system. These results are consistent with the previous DC susceptibility, neutron scattering, and electron spin resonance (ESR) experiments.
2013-12-15