Electronic states in the spin-density wave phase of organic conductors: roles of the coexisting 2kF and 4kF charge–density waves

Many kinds of experiments have suggested the presence of a subphase structure in the SDW state of (TMTSF)2PF6 and its family. However, its origin is unclear. We studied electronic properties of the SDW state by diffuse X-ray, thermopower and magnetic measurements. It was found that the amplitude of the 2kF and 4kF CDWs coexisting with the SDW decreases with decreasing temperature. The thermopower and the magnetic susceptibility measurements show anomalies in their temperature dependence in the SDW state. It is conjectured that a possible change in the SDW wave vector causes the subphase structure leading to these anomalies in the electronic and structural properties.