Specific-heat study of the anomalous quantum limit of (TMTSF)2ClO4.

Abstract

We report calorimetric measurements of the organic conductor (TMTSF${)}_{2}$${\mathrm{ClO}}_{4}$ in the quantum limit. In addition to the field-induced spin-density-wave (FISDW) phases, we have measured the magnetic-field-dependent specific heat associated with the recently discovered reentrant phase. In terms of a semiempirical model, we find that the reentrant transition is second order, but that the electronic density of states is greatly reduced in the reentrant phase. We also observe a specific-heat signal corresponding to the anomalous ``fast oscillations'' which are known to coexist with the FISDW phases