Moving flux quanta cool superconductors by a microwave breath
Moving flux quanta cool superconductors by a microwave breath
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DOI：
10.1038/s42005-020-0329-z
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发表时间：
2020-04-02
影响因子：
5.5
通讯作者：
Aliev, F. G.
中科院分区：
文献类型：
--
作者：
Dobrovolskiy, O. V.;Gonzalez-Ruano, C.;Aliev, F. G.
几乎任何超导体的使用都隐含着一种非平衡态。值得注意的是，尽管足够高功率的GHz电磁场可以激发超导电性，但磁通量子的快速运动(Abrikosov涡旋)可以触发超导状态的不稳定突然熄灭。在这里，我们表明，通过调节加在直流偏置电流中的微波交流激励的功率和频率，可以提前或延迟Nb薄膜中涡旋态的动态猝灭。实验结果得到了与时间相关的Ginzburg-Landau模拟的支持，并且可以基于“呼吸移动热点”模型定性地解释它们，该模型意味着准粒子沿着其核心大小随时间变化的运动流子的轨迹进行加热和冷却的竞争。此外，我们还证明了激发效应对第二类超导体热力学和输运性质的普适性，超导电性可以在大电流下被猝灭，并且可以被高功率的微波交流激励所激发。本文研究了存在涡旋的Nb超导体中的直流和微波驱动的猝灭，以及引起超导态的激发和猝灭竞争的因素。
Almost any use of a superconductor implies a non-equilibrium state. Remarkably, while a sufficiently high-power electromagnetic field of GHz frequency can stimulate superconductivity, fast motion of magnetic flux quanta (Abrikosov vortices) can trigger an instability abruptly quenching the superconducting state. Here, we show that such dynamical quenching of the vortex state in Nb thin films can be advanced or delayed by tuning the power and frequency of the microwave ac stimulus added to a dc bias current. The experimental findings are supported by time-dependent Ginzburg-Landau simulations and they can be explained, qualitatively, based on a model of "breathing mobile hot spots", implying a competition of heating and cooling of quasiparticles along the trajectories of moving fluxons whose core sizes vary in time. In addition, we demonstrate universality of the stimulation effect on the thermodynamic and transport properties of type II superconductors.Superconductivity can be quenched at large dc currents and it can be stimulated by a high-power microwave ac stimulus. Here, the authors investigate the dc- and microwave-driven quenching in a Nb superconductor in the presence of vortices and the factors contributing to the competition between the stimulation and quenching of the superconducting state.