Electron correlation and two dimensionality in the spin-density-wave phase of (TMTTF)2Br under pressure -: art. no. 212404

The incommensurate spin-density-wave (SDW) phase in (TMTTF)(2)Br was investigated through transport measurements under pressure and magnetic fields parallel to the c(*) axis. For the incommensurate SDW phase of (TMTTF)(2)Br stabilized above 0.5 GPa, the SDW transition temperature T-SDW increases with the applied magnetic field. The field dependence of T-SDW is described by a quadratic behavior and the coefficient of the quadratic term increases with increasing pressure. These results are consistent with the prediction of the mean-field theory based on the suppression of the SDW transition by two dimensionality. From the relation between the coefficient of the quadratic term and T-SDW at zero magnetic field, we determined the role of electron correlation and two dimensionality in the SDW phase of (TMTTF)(2)Br under pressure and found that the SDW transition in (TMTTF)(2)Br can be well explained within the mean-field theory by taking into account the reduction of the coupling constant N(0)I by pressure.