Abstract

The current–voltage characteristics (CVCs) of wide superconducting NbN films in magnetic fields up to 8 T are studied in this work. Linear portions that do not change the tilt angle in magnetic fields below the superconducting transition temperature have been found in the CVCs of such films. A model of viscous magnetic flux under conditions of rigid fixation of a part of the vortex system is proposed to explain these linear portions. The magnetic field dependences of the depinning current and the vortex motion velocity are found within the model of collective pinning of the vortex lattice. The value of the disorder parameter is obtained, and the depairing current density is estimated. From the Larkin–Ovchinnikov theory of vortex lattice instability, the dependence of the energy relaxation time of quasiparticles on the magnetic field is determined.

中文翻译：

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NbN超导薄膜在磁场中的电流-电压特性

摘要

在这项工作中，研究了宽超导NbN薄膜在高达8 T的磁场中的电流-电压特性（CVC）。在这样的膜的CVC中发现了在低于超导转变温度的磁场中不改变倾斜角的线性部分。提出了在涡旋系统一部分刚性固定的条件下的粘性磁通量模型来解释这些线性部分。在旋涡晶格的集体固定模型中，发现了固定电流与旋涡运动速度的磁场依赖性。获得无序参数的值，并估计去耦电流密度。根据拉金-奥夫钦尼科夫涡旋格不稳定性理论，确定了准粒子的能量弛豫时间对磁场的依赖性。