Imprinting superconducting vortex footsteps in a magnetic layer
Imprinting superconducting vortex footsteps in a magnetic layer
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DOI：
10.1038/srep27159
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发表时间：
2016-06-06
影响因子：
4.6
通讯作者：
Silhanek, Alejandro V.
中科院分区：
文献类型：
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作者：
Brisbois, Jeremy;Motta, Maycon;Silhanek, Alejandro V.
磁层的局部极化是一种众所周知的存储信息的方法，已经在许多应用中找到了它的位置，例如流行的磁性绘图板玩具或广泛的信用卡和计算机硬盘驱动器。在这里，我们的实验表明，一个类似的原理可以应用于压印的量子单位的磁通量（涡旋），在超导薄膜（Nb），到一个软磁性层坡莫合金（Py）的轨迹。与磁性绘图板完全类似，涡旋充当微小的磁性划线器，在Py板中留下极化磁性介质的尾流。利用磁光成像技术研究了超导涡旋与铁磁畴之间的相互作用。对于厚的Py层，条纹磁畴图案引导在Nb膜中的平滑磁通穿透以及突然的涡旋雪崩。然而，在没有条纹畴的薄Py层中，超导涡旋沿着它们的路径留下最清晰的局部极化磁矩印记。在所有情况下，我们观察到磁通量在磁性层的边界处被延迟。我们的发现开启了对超导涡旋轨迹的优化磁记录的探索。
Local polarization of a magnetic layer, a well-known method for storing information, has found its place in numerous applications such as the popular magnetic drawing board toy or the widespread credit cards and computer hard drives. Here we experimentally show that a similar principle can be applied for imprinting the trajectory of quantum units of flux ( vortices), travelling in a superconducting film (Nb), into a soft magnetic layer of permalloy (Py). In full analogy with the magnetic drawing board, vortices act as tiny magnetic scribers leaving a wake of polarized magnetic media in the Py board. The mutual interaction between superconducting vortices and ferromagnetic domains has been investigated by the magneto-optical imaging technique. For thick Py layers, the stripe magnetic domain pattern guides both the smooth magnetic flux penetration as well as the abrupt vortex avalanches in the Nb film. It is however in thin Py layers without stripe domains where superconducting vortices leave the clearest imprints of locally polarized magnetic moment along their paths. In all cases, we observe that the flux is delayed at the border of the magnetic layer. Our findings open the quest for optimizing magnetic recording of superconducting vortex trajectories.