Formula omitted] NMR in spin density wave phase of (TMTSF) 2PF 6

Abstract

We have investigated the multi-phase structure in the incommensurate spin density wave (SDW) phase in (TMTSF) 2PF 6 with 1 H NMR measurement. The temperature dependence of spin lattice relaxation rate T 1 −1 was measured at ambient pressure with varying the magnetic field up to 2.0 T. The divergent peak of T 1 −1 was observed at the temperature T ∗ well below the SDW transition temperature T SDW in each field. The peak height decreases with increasing the magnetic field, suggesting the divergent increase of low frequency fluctuation of local field at T ∗. These behaviors indicate that the phase transition with the magnetic fluctuation, which divides the incommensurate SDW phase into two sub-phases, occurs at T ∗. With increasing the magnetic field, the peak temperature T ∗ increases from 3 K at 0.3 T to 3.7 K at 1.2 T and shows a saturation behavior above 1.2 T. This indicates that the low temperature SDW sub-phase is stabilized more under the magnetic field around 1 T.