Jones Antony, Lam Simon K H, Du Jia, Rubanov Sergey, Pan Alexey V
Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, New South Wales 2522, Australia.
CSIRO Manufacturing, Bradfield Road, West Lindfield, New South Wales 2070, Australia.
ACS Appl Mater Interfaces. 2020 Jun 10;12(23):26170-26176. doi: 10.1021/acsami.0c04658. Epub 2020 May 29.
Design of flux profile and guided motion of magnetic flux quanta (also known as vortices) are central issues for functionality of superconducting devices. Anchoring vortex movement by trapping flux lines through the use of defects and preventing vortex entry by shielding magnetic field have been broadly explored, which can also enable reduction of noise for optimal device operation. Removing vortices entirely via the so-called ratchet effect (employing an asymmetric energy potential) is another alternative. This ratcheting potential is also used in DNA splitting, particle separation, surface atom electromigration, and electrophoresis. Utilizing a superconductor with the ratchet vortex pinning potential induces a dominant motion direction, which can be used to pump flux out from device functional zones. In this work, a varying thickness superconductor with its tailored intrinsic pinning mechanism has been simulated and proven to provide this preferential vortex motion. We demonstrate both theoretically and experimentally that a varying thickness superconducting ratchet is indeed possible. Furthermore, the sawtooth shape of the bridge provides a tunability to the preferred vortex motion direction, dependent on the ramp gradient and intrinsic pinning strength.
磁通分布的设计以及磁通量量子（也称为涡旋）的引导运动是超导器件功能的核心问题。通过利用缺陷捕获磁通线来锚定涡旋运动以及通过屏蔽磁场来防止涡旋进入已得到广泛研究，这也能够降低噪声以实现器件的最佳运行。通过所谓的棘轮效应（采用不对称能量势）完全去除涡旋是另一种选择。这种棘轮势也用于DNA分裂、粒子分离、表面原子电迁移和电泳。利用具有棘轮涡旋钉扎势的超导体可诱导出主导运动方向，该方向可用于将磁通从器件功能区抽出。在这项工作中，对具有定制本征钉扎机制的变厚度超导体进行了模拟，并证明其能提供这种优先的涡旋运动。我们在理论和实验上都证明了变厚度超导棘轮确实是可行的。此外，桥的锯齿形状为优先涡旋运动方向提供了可调性，这取决于斜坡梯度和本征钉扎强度。
