Thermodynamics of Field-Induced in Bechgaard Salts.

By using Yamaji's quasi one dimensional tight binding model, the thermodynamics of the field induced spin density wave (FISDW) phase of the Bechgaard salts (TMTSF)_2X are studied theoretically. It is shown that the model can explain not only the temperature pressure phase diagram but also the cascade phase diagram of the FISDW states. It is found that quantized nesting of the Fermi surface (Q = (2k_{F} + Nk, {piover b} + q_ {y}, {piover c} + q_{z})) is essential to obtain the cascade phase diagram. It predicts there is a dip in the FISDW phase diagram when the magnetic field lies in the b-c plane with phi ~eq { rm tan}^{-1}({bover c}) away from the c-axis. Both the excess magnetization and the ground state condensation energy are calculated via different approximations. (Copies available exclusively from Micrographics Department, Doheny Library, USC, Los Angeles, CA 90089-0182.).