The incommensurate spin-density-wave (SDW) phase in (TMTTF)2Br was investigated through transport measurements under pressure and magnetic fields parallel to the c∗ axis. For the incommensurate SDW phase of (TMTTF)2Br stabilized above 0.5 GPa, the SDW transition temperature TSDW increases with the applied magnetic field. The field dependence of TSDW 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 TSDW at zero magnetic field, we determined the role of electron correlation and two dimensionality in the SDW phase of (TMTTF)2Br under pressure and found that the SDW transition in (TMTTF)2Br can be well explained within the mean field theory by taking into account the reduction of the coupling constant N(0)I by pressure.
@article{arxiv.cond-mat/0306383,
title = {Electron correlation and two dimensionality in the spin-density-wave phase of (TMTTF)$_2$Br under pressure},
author = {A. Ishikawa and N. Matsunaga and K. Nomura and T. Sasaki and T. Nakamura and T. Takahashi and G. Saito},
journal= {arXiv preprint arXiv:cond-mat/0306383},
year = {2009}
}