Topics
- Superconducting fluctuations in κ-(BEDT-TTF)2Cu[N(CN)2]Br
- Commensurability of SDW in (TMTSF)2PF6
- Charge ordered state in β''-(BEDT-TTF)3Cl2⋅2H2O
- Correlation between non-Fermi-liquid behavior and anti-ferromagnetic fluctuation in (TMTSF)2PF6
- Low-frequency dynamics of κ-(BEDT-TTF)2Cu(NCS)2
- Zero-gap-semiconductor state of α-(BEDT-TTF)2I3
An organic conductor (TMTSF)2PF6 (TMTSF : tetramethyltetraselenafulvalene) is well known for the first organic material showing superconductivity. The mechanism of this superconductivity has not been clarified yet and has widely been studied. For superconductivity, attractive interactions between electrons, which are probably caused by antiferromagnetic fluctuations, are required. Recent years, in (TMTSF)2PF6, the correlation between non-Fermi-liquid (NFL) behavior of resistivity and disappearance of superconductivity has been reported [Phys. Rev. B 80, 214531], where it is suggested that both NFL behavior of the resistivity and disappearance of superconductivity are caused by antiferromagnetic fluctuations.
In order to investigate magnetic characters, the nuclear magnetic resonance (NMR) measurement is one of the best tools available, and NMR measurements have already been performed with various nuclei in (TMTSF)2PF6. However, in 13C-NMR measurement with conventional (TMTSF)2PF6, observed spectra get complex because of the Pake doublet effect which is induced by 13C=13C spin coupling in the TSF molecule. As a result, the systematic 13C-NMR measurement has not been performed. In this work, (in order to suppress the Pake doublet effect) we synthesized the enriched (TMTSF)2PF6 for which only one side of the C=C bond in the TSF molecule is enriched with 13C, succeeded in suppressing the Pake doublet effect and carried out 13C-NMR to investigate the origin of the NFL behavior.
Figure 1 displays connections between Tc and C which corresponds to amplitude of antiferromagnetic fluctuations. Tc and C decrease with increasing pressure and the connection between the emergence of FL behavior and the disappearance of superconductivity suggests that antiferromagnetic fluctuations are related to the superconductivity in (TMTSF)2PF6. For these experiments, we showed strong correlation between disappearance of antiferromagnetic fluctuations and the emergence of FL behavior.
The paper titled gCorrelation between non-Fermi-liquid behavior and anti-ferromagnetic fluctuation in (TMTSF)2PF6h has been published in Phys. Rev. B 84, 045123 (2011).