Upper Frequency Limits for Vortex Guiding and Ratchet Effects
Upper Frequency Limits for Vortex Guiding and Ratchet Effects
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DOI：
10.1103/physrevapplied.13.024012
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发表时间：
2020-02-07
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.;Begun, E.;Huth, M.
磁通量子的引导和整流运动是控制纳米结构超导体磁阻响应的重要效应。虽然在低交流频率这些影响是相当好的理解，他们的表现在较高的交流频率仍然很少调查。在这里，我们探索的频率上限的指导和整流净运动的超导涡旋在外延铌膜装饰铁磁纳米条纹。通过结合宽带电子光谱与电阻测量，我们发现，整流电压消失在一个几何定义的频率约700 MHz。相比之下，涡流引导相关的低交流损耗响应持续高达约2 GHz。该值对应于与由纳米条引起的搓板钉扎电位相关联的脱钉扎频率f（d）（s），其表现出相称的涡旋晶格配置的峰值。通过相对于纳米条以角度α施加直流和微波交流电流的总和，发现f（d）（s）（α）的角度依赖性与脱钉电流的角度依赖性相关。总之，我们的研究结果表明，具有较高f（d）（s）的超导体应该有利于在千兆赫交流频率范围内进行有效的涡旋操纵。
The guided and rectified motion of magnetic flux quanta are important effects governing the magnetoresistive response of nanostructured superconductors. While at low ac frequencies these effects are rather well understood, their manifestations at higher ac frequencies remain poorly investigated. Here, we explore the upper frequency limits for guided and rectified net motion of superconducting vortices in epitaxial Nb films decorated with ferromagnetic nanostripes. By combining broadband electrical spectroscopy with resistance measurements, we reveal that the rectified voltage vanishes at a geometrically defined frequency of about 700 MHz. By contrast, a vortex-guiding-related low-ac-loss response persists up to about 2 GHz. This value corresponds to the depinning frequency f(d)(s) associated with the washboard pinning potential induced by the nanostripes, which exhibits peaks for commensurate vortex-lattice configurations. By applying a sum of dc and microwave ac currents at an angle alpha with respect to the nanostripes, the angle dependence of f(d)(s) (alpha) is found to be correlated with the angle dependence of the depinning current. In all, our findings suggest that superconductors with higher f(d)(s) should be favorable for efficient vortex manipulation in the gigahertz ac frequency range.