No abstract

We present 13C NMR lineshapes and spin lattice relaxation measurements of (TMTTF),Br and (TMTSF),PF6 in the spin density wave (SDW) state. We c o n f m that (TMTSF),PF6 has an incommensurate SDW and show that the phason mode is dominant in the relaxation. We prove that (TMTTF)2Br is commensurate and estimate the SDW amplitude. No phason contribution to the relaxation is observed in this compound. The implications for theory are discussed.

We report on joint conduction noise and 13 C NMR measurements in the sliding spin-density wave (SDW) state of (TMTSF) 2 PF 63 where TMTSF is tetramethyltetraselenafulvalene. The noise distribution is narrow and scales linearly with current. Narrowing of the NMR line was observed simultaneously. The comparison of these two sets of data shows that the sliding motion is highly coherent and that the conduction noise frequency is equal to the winding rate of the SDW. In the depinned volume, a substantial fraction of the conduction electrons participate in the sliding mode. Consequences on the origin of conduction noise and on other transport measurements are discussed.