Magnetic properties of the spin-density wave in (TMTSF)2X and (TMTTF)2Br

Magnetic properties of the spin density wave (SDW) phase in (TMTSF)2X (X=AsF6, PF6) and (TMTTF)2Br were investigated through analyses of 1H-NMR and static magnetization measurements. A divergent peak was observed, at the temperature T* well below the SDW transition temperature, in the 1H spin-lattice relaxation rate in the incommensurate SDW phase of (TMTSF)2X. A decrease of the differential magnetic susceptibility of (TMTSF)2X with the field parallel to the a-axis was observed around T*. This anomaly indicates a difference of the spin canting above and below T* which divides the SDW phase. In the measurements of magnetic susceptibility on the commensurate SDW phase of (TMTTF)2Br, a large decrease of the spin susceptibility was observed above TSDW and non-activated type behavior in the b'-axis susceptibility is observed below the spin-flop field at low temperature. The data are discussed on the basis of commensurability. (orig.)