Calorimetric Study on Metal-Insulator Transition of Quasi-One-Dimensional BaVS₃

The specific heat of BaVS₃, which undergoes a metal-insulator transition at T_MI = 70 K, was measured in the temperature range of 1.4 K to 300 K. A specific heat anomaly was found at T_MI. The entropy change associated with this anomaly is estimated to be 4.7 J/K mol, which is close to R ln.2. the expected magnetic entropy for S = 1/2 spins of V atoms. At low temperatures, a T-linear contribution of the specific heat with an apparent γ value of 15.7 mJ/K² mol was observed in spite of the absence of conduction electrons. This T-linear contribution may be attributed to spin wave excitations for a one-dimensional antiferromagnet.