Rapid oscillation and Fermi-surface reconstruction due to spin-density-wave formation in the organic conductor (TMTSF)2PF6

Abstract

Resistance and magnetic torque for the quasi-one-dimensional organic conductor (TMTSF${)}_{2}$${\mathrm{PF}}_{6}$ have been measured over a wide magnetic field and temperature ranges to investigate the correlation between the rapid oscillation (RO) and the spin-density-wave (SDW) formation. The RO with the frequency of 220 T is found in the resistance above 15 T for all the current directions and in the ab-plane Hall resistance in the SDW phase. The RO amplitude has a sharp peak around 3 K, which is associated with a maximum of the normalized magnetoresistance. The magnetic torque shows a jump at the SDW transition tempera- ture (\ensuremath{\sim}11.5 K) with decreasing temperature, and then a broad maximum around 3 K (${\mathrm{T}}_{\mathrm{max}}$) suggesting a subphase transition. ${\mathrm{T}}_{\mathrm{max}}$ slightly shifts to a high temperature with increasing magnetic field. A possible mechanism of the RO is discussed on the basis of the Fermi surface reconstruction due to the SDW formation.