Fast Dynamics of Guided Magnetic Flux Quanta
Fast Dynamics of Guided Magnetic Flux Quanta
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DOI：
10.1103/physrevapplied.11.054064
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发表时间：
2019-05-23
影响因子：
4.6
通讯作者：
Huth, M.
中科院分区：
文献类型：
--
作者：
Dobrovolskiy, O., V;Bevz, V. M.;Huth, M.
超导体中阿布里科索夫涡旋的动力学通常限制在涡旋速度nu接近1 km/s时，高于此速度的样品会突然过渡到正常状态。在拉金-奥夫钦尼科夫框架中，在临界温度附近，这种转变是由于准粒子离开涡旋核心导致粘性阻力系数降低而引发的通量流动不稳定。虽然现有的不稳定性理论依赖于涡旋速度的均匀空间分布，但nu的测量值（平均值）总是小于可能的最大值，因为v的分布从未达到delta函数形状。在这里，通过引导磁通量子相对于钴纳米条纹阵列倾斜15度，我们将涡旋加速到3-6 km/s。这些在参考生长的Nb薄膜中超过v几乎一个数量级，并且仅比迄今为止在超导体中观察到的最大涡旋速度小约3倍。我们认为，当所有涡旋以相同的钉钉强度在通道中运动并表现出非常窄的nu分布时，会出现如此高的nu值，这是集体动态排序的结果。我们的发现揭示了众所周知的涡旋引导效应，为超快涡旋动力学的研究开辟了前景。
The dynamics of Abrikosov vortices in superconductors is usually limited to vortex velocities nu approximate to 1 km/s, above which samples abruptly transit into the normal state. In the Larkin-Ovchinnikov framework, near the critical temperature, this transition is because of a flux-flow instability triggered by the reduction of the viscous drag coefficient due to the quasiparticles leaving the vortex cores. While the existing instability theories rely upon a uniform spatial distribution of vortex velocities, the measured (mean) value of nu is always smaller than the maximal possible one, since the distribution of v never reaches the delta-functional shape. Here, by guiding magnetic flux quanta at a tilt angle of 15 degrees with respect to a Co nanostripe array, we speed up vortices to 3-6 km/s. These exceed v in the reference as-grown Nb films by almost an order of magnitude and are only a factor of about 3 smaller than the maximal vortex velocities observed in superconductors so far. We argue that such high nu values appear in consequence of a collective dynamic ordering when all vortices move in the channels with the same pinning strength and exhibit a very narrow distribution of nu. Our findings render the well-known vortex guiding effect to open prospects for investigations of ultrafast vortex dynamics.