Research on superconductivity transition phenomena of organic conductor through quantum oscillation effects.

有机超导体K，-(BEDT-TTEOsCuCNCS)的本征层状结构增强了其超导涨落效应。因此，超导转变是模糊的，没有明显的上临界场。为了深入了解超导转变的特性，研究了超导在量子振荡中出现的损耗，从超导涨落的角度分析了与布里斯托尔大学合作测量的De Haas-van Alphen效应中出现的超导损耗因子。在0.5K以下，对起伏的超导带隙进行了定量澄清。它与外加磁场方向的夹角关系表明了超导电性的二维性和相应的涨落效应。为了研究正常状态下与二维的相关性，测量了电阻率各向异性与温度的关系，测量了在常温和2kbar压力下，温度降至0.55K，磁场高达9T时的Shubnikovde Haas效应。在6.8T以上观察到了Shubnikovde Haas效应，在6.8~7.3T的磁场范围内，发现了振荡的附加衰减。在超导电性被抑制的压力下，没有阻尼。这清楚地表明，这种衰减是由超导电性引起的。定量分析并不成功，因为在0.55K下测量的磁场窗口太小，建议使用稀释式制冷机进行进一步的低温测量。我们还研究了其他K型BEDT-TTF盐和Bedo-TTF盐，但在超导转变区附近没有测量到量子振荡效应，至少下降到0.55K。

Organic superconductor K, -(BEDT-TTEOsCuCNCS^ exhibits superconducting fluctuation effects enhanced by the inherent layered structure. As a result, the superconductivity transition is smeared with no distinct upper critical field. In order to get insight into the superconductivity transition characteristics, damping due to superconductivity appearing on the quantum oscillations is studied.Superconductivity damping factor appearing on the de Haas-van alphen effect, which was measured as a collaboration project with University of Bristol, is analyzed in terms of the superconducting fluctuation. Up to 0.5K, fluctuating superconductivity gap is clarified quantitatively. Its angle dependence with respect to the direction of the external magnetic field indicates the two-dimensionality of the superconductivity and relevant fluctuation effects. In order to investigate the correlation with the two-dimensionality in the normal state, temperature dependence of the anisotropy of resistivity is measured.The Shubnikovde Haas effect, the quantum oscillation on the resistivity, is measured at ambilent and 2 kbar pressure, under temperature down to 0.55 K and magnetic field up to 9 T generated by the magnet purchased with the grant. The Shubnikovde Haas effect is observed above 6.8 T. In a magnetic field region between 6.8 and 7.3 T, additional damping of the oscillation is found. Under pressure in which superconductivity is suppressed, the damping is absent. This indicates clearly that the damping is caused by the superconductivity. The quantitative analysis is not successful because the magnetic field window is too small at 0.55 K Measurements at further low temperature using dilution' refrigerator is encouraged.Other K-type BEDT-TTF salts and BEDO-TTF salts are also investigated, however, no quantum oscillation effect was measured near the superconductivity transition region, at least down to 0.55 K.