Field-induced SDW phase diagram of (TMTSF)₂PF₆ at high magnetic fields

Magnetoresistance measurements have been carried out along the highly conducting a-axis in the field-induced SDW (FISDW) phase of (TMTSF) ₂PF₆ under 1.0 GPa, with the field up to 27 T parallel to the lowest-conductivity direction c*. We have determined the phase boundary between the last semimetallic FISDW phase with n= 1 and the FISDW insulating phase with n = 0 and found that the semimetallic FISDW phase existed above the transition temperature of the FISDW insulating phase at least up to 24 T. These results suggest the necessity of the theoretical calculation for more realistic quasi-one-dimensional Fermi surface to explain the FISDW phase of (TMTSF)₂PF₆.