Anomalous specific heat of (DMe-DCNQI d2[1,1;0]1−xd4[2,2;0]x)2Cu-system

A (DMe-DCNQI) 2 Cu crystal composed of molecules having deuterated methyl groups (CH 2 D) shows a typical Schottky type specific heat It is caused by orientation degree of freedom of CH 2 D. The system that has methyl groups with two deuterium atoms (CHD 2 ), on the other hand, shows a specific heat that apparently differs from the Schottky type. Based on the thermal measurement on the mixed crystals, we propose a possible mechanism of the anomalous specific heat in the CHD 2 system.