Correlation between rapid oscillation and phase diagram in quasi-one-dimensional organic conductor (TMTSF)2ClO4

Resistance and magnetic torque measurements for the quasi-one-dimensional organic conductor (TMTSF)2ClO4 have been systematically performed in the low field (8 T<B<26 T) and high field (B>26 T) spin-density-wave phases (SDW I and II phases). We found two different rapid oscillations (RO A and B) in SDW I phase, but a single oscillation (RO C) in SDW II phase in the a- and c-axis resistance and the magnetic torque. All the ROs have the same frequency. The Hall resistance is well quantized in the SDW phase below 25 T, and then starts oscillating with the sign reversal above 26 T, which can be assigned to RO C. The RO B and C may be ascribed to a conventional Shubnikov–de Haas (SdH) effect due to magnetic breakdown (MB) orbits reconstructed by the SDW nesting and the ClO4 anion order (AO). However, the origin of the RO A, whose amplitude steeply decreases with decreasing temperature below ∼2.5 K, is not clarified yet.