Schneider R, Zaitsev A G, Fuchs D, von Löhneysen H
Institut für Festkörperphysik, Karlsruher Institut für Technologie, D-76021 Karlsruhe, Germany.
J Phys Condens Matter. 2014 Nov 12;26(45):455701. doi: 10.1088/0953-8984/26/45/455701. Epub 2014 Oct 16.
Temperature-dependent electronic transport in the vicinity of the superconducting transition is reported for quasi-two-dimensional textured FeSe thin films. The conspicuous rounding of the resistive transitions and large transition widths are indications of excess conductivity due to thermal Cooper-pair fluctuations, which can be well-described by the two-dimensional Aslamazov-Larkin theory. The Halperin-Nelson form of the sheet resistance between the phase-ordering temperature TBKT and the mean-field temperature TMF, and the power-law behaviour of the voltage-current characteristics, with a distinctive jump of the exponent at TBKT, are indicative of a Berezinskii-Kosterlitz-Thouless transition. The complementary results suggest a two-dimensional character of superconductivity in the FeSe films and allow a quantitative estimate of the Ginzburg number Gi.
报道了准二维织构FeSe薄膜在超导转变附近的温度依赖电子输运。电阻转变的明显圆滑和较大的转变宽度表明存在由于热库珀对涨落导致的额外电导率，这可以用二维阿斯拉马佐夫 - 拉金理论很好地描述。在相序温度TBKT和平均场温度TMF之间的薄层电阻的哈尔珀林 - 尼尔森形式，以及电压 - 电流特性的幂律行为，在TBKT处指数有明显跳跃，表明存在贝雷津斯基 - 科斯特利茨 - Thouless转变。这些互补的结果表明FeSe薄膜中超导的二维特性，并允许对金兹堡数Gi进行定量估计。
