Heat capacity anomaly of CeCu_2.05Si₂ under magnetic fields

Heat capacity measurements of CeCu_2.05Si₂ have been carried out at temperatures down to 0.1 K under magnetic field up to 13 T. The heat capacity divided by temperature C/T has revealed as a characteristic feature that the peak of C/T shifts down to around 0.5 K with increasing field up to 7 T, whereafter it shifts up again to around 0.6 K at 13T. In the first case, a peak appears around the phase boundary (labeled A) first found in NMR and magnetoresistance. Most remarkably, in the latter case, the peak coincides with the new phase boundary (labeled B) identified recently by elastic constant and thermal expansion measurements.