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Electron correlation and two dimensionality in the spin-density-wave phase of (TMTTF)$_2$Br under pressure

A. Ishikawa·N. Matsunaga·K. Nomura·T. Sasaki·T. Nakamura·T. Takahashi·G. Saito
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Abstract

The incommensurate spin-density-wave (SDW) phase in (TMTTF)$_2$Br was investigated through transport measurements under pressure and magnetic fields parallel to the $c^{\ast}$ axis. For the incommensurate SDW phase of (TMTTF)$_2$Br stabilized above 0.5 GPa, the SDW transition temperature $T_{\rm SDW}$ increases with the applied magnetic field. The field dependence of $T_{\rm SDW}$ 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 $T_{\rm SDW}$ 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.

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A. Ishikawa, N. Matsunaga, K. Nomura, T. Sasaki, T. Nakamura, T. Takahashi, G. Saito. 2003-06-14. Electron correlation and two dimensionality in the spin-density-wave phase of (TMTTF)$_2$Br under pressure. https://doi.org/10.1103/physrevb.67.212404

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