GLASS-TRANSITION IN THE SPIN-DENSITY-WAVE PHASE OF (TMTSF)2PF6 INVESTIGATED BY CALORIMETRIC MEASUREMENTS

We report on detailed kinetic investigation of the specific heat anomaly of the spin density wave phase of (TMTSF)2PF6 in the temperature range 2.5-5K. We point out the crucial role of kinetic conditions and of previous thermal history, such as isothermal annealing, which causes large hysteretic phenomena. This gives strong support to the origin of the anomaly in a glass transition which can be described in the general framework of freezing of supercooled liquids. For the unannealed system, T(g) = 3.45 K.