Phase diagram of the field-induced spin density wave state in (TMTSF)2ClO4(TMTSF)2ClO4 deduced from the specific heat measurements

We have measured the specific heat of the quasi-one dimensional organic conductor (TMTSF)2ClO4(TMTSF)2ClO4. The clear phase diagram of the field-induced spin density wave state was obtained from the density plot of the specific heat. We observed the reentrance to the metallic state and the tetracritical behavior quite clearly, though there is no evidence of the ”tree-like” structure.