We have investigated the low temperature isothermal current-voltage characteristics of FeSe epitaxial films with thickness of ∼ 360 nm at different magnetic fields parallel to the c axis. At zero magnetic field, with decreasing temperature a Berezinskii–Kosterlitz–Thouless transition, which often appears in two-dimensional (2D) superconductors, is observed. The current dependence of the voltage obeys the scaling relation V ∼ I 3 at the transition temperature ##IMG## [http://ej.iop.org/images/0953-2048/33/10/105010/sustababebieqn1.gif] {$T_{\rm BKT}\approx4.7$} K, and the temperature dependence of sheet resistance follows the prediction of the Halperin-Nelson formula in the vicinity of ##IMG## [http://ej.iop.org/images/0953-2048/33/10/105010/sustababebieqn2.gif] {$T_{\rm BKT}$} . When a magnetic field with magnitude 0.1 T ##IMG## [http://ej.iop.org/images/...] {$\lesssim \mu_0 H \lesssim 6$}

中文翻译：

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FeSe超导薄膜中的涡旋态

我们研究了在平行于c轴的不同磁场下厚度约为360 nm的FeSe外延膜的低温等温电流-电压特性。在零磁场下，随着温度降低，观察到Berezinskii-Kosterlitz-Thouless跃迁，该跃迁通常出现在二维（2D）超导体中。电压的电流依赖性在转变温度下服从比例关系V〜I 3 [＃IMG ##] [http://ej.iop.org/images/0953-2048/33/10/105010/sustababebieqn1.gif] {$ T _ {\ rm BKT} \ approx4.7 $} K，并且薄层电阻的温度依赖性遵循## IMG ## [http：//ej.iop附近]的Halperin-Nelson公式的预测。 org / images / 0953-2048 / 33/10/105010 / sustababebieqn2.gif] {$ T _ {\ rm BKT} $}。当磁场强度为0.1 T ## IMG ## [http：//ej.iop。