由当地接触式扫描涡操纵SQUID研究
Summary
We present a protocol for manipulation of individual vortices in thin superconducting films, using local mechanical contact. The method does not include applying current, magnetic field or additional fabrication steps.
Abstract
Local, deterministic manipulation of individual vortices in type 2 superconductors is challenging. The ability to control the position of individual vortices is necessary in order to study how vortices interact with each other, with the lattice, and with other magnetic objects. Here, we present a protocol for vortex manipulation in thin superconducting films by local contact, without applying current or magnetic field. Vortices are imaged using a scanning superconducting quantum interference device (SQUID), and vertical stress is applied to the sample by pushing the tip of a silicon chip into the sample, using a piezoelectric element. Vortices are moved by tapping the sample or sweeping it with the silicon tip. Our method allows for effective manipulation of individual vortices, without damaging the film or affecting its topography. We demonstrate how vortices were relocated to distances of up to 0.8 mm. The vortices remained stable at their new location up to five days. With this method, we can control vortices and move them to form complex configurations. This technique for vortex manipulation could also be implemented in applications such as vortex based logic devices.
Introduction
涡流是在纳米磁性物体，形成在2型超导体在外部磁场的存在。在一无缺陷样品，旋涡可以自由移动。然而，在材料的结果，其中对于旋涡能量上有利的降低超导区域不同的缺陷。涡流倾向于装饰这些区域，也被称为钉扎部位。在这种情况下，移动一个涡流所需的力必须大于钉扎力越大。的涡流，如涡流密度，相互作用的强度和范围的性质，可以通过外部场，温度，或样品的几何形状容易地确定。控制这些性质的能力使得它们成为凝聚态行为可以容易地调整，以及合适的候选者良好的模型系统用于电子应用的1，2。个别旋涡的位置的控制是这样的LO的设计必需gical元素。
磁性纳米粒子的机械控制之前已经完成。 Kalisky 等。最近使用扫描超导量子干涉仪（SQUID）研究局部机械应力对铁磁补丁复合氧化物接口3的影响。他们能够通过扫描在接触来改变贴片的方向，按压SQUID的尖端到样品，在这个过程施加到1μN的力。我们已在以移动涡流应用于我们的协议类似的方法。
在涡流操纵现有的研究，运动通过施加电流到样品来实现，从而产生洛伦兹力4，5，6。虽然这种方法是有效的，它不是本地的，并且为了控制单个涡流，则需要额外的制造。涡也可以MANIPulated通过用磁力显微镜（MFM）或用SQUID励磁线圈7,8施加外部磁场，例如。这个方法是有效的和局部的，但这些工具所施加的力小，并且只能在高温下，接近超导体的临界温度克服钉扎力。我们的协议允许在低温（4 K）的有效，本地操作没有样品的额外的制造。
我们用扫描显微镜SQUID形象旋涡。该传感器被制造被抛光成一个角，并粘接在柔性悬臂的硅芯片上。悬臂用于表面的电容传感。该芯片被放置在一个角度的样品，使得接触点是在芯片的顶端。我们通过推动芯片放入样品申请高达2μN的力量。我们移动相对SQUID样品由压电元件。我们移动旋涡通过点击硅尖旁边的一个旋涡，或通过清扫它，触摸旋涡。
Protocol
Representative Results
Discussion
旋涡的操纵成功取决于几个关键步骤。它以对准传感器成一角度，以使得芯片的末端将是第一个，使与样品接触是重要的。第二，要注意，施加在样品上的力是通过该芯片安装在悬臂的机械特性决定是很重要的。在弹性体制，所施加的力成比例的偏转中，x，根据虎克定律：
F = -kx
其中k是弹簧常数，由杨氏模量的材料制成，并且它的物理尺寸决定的，并且由下式给出
…
Divulgations
The authors have nothing to disclose.
Acknowledgements
我们感谢A.从巴伊兰大学Sharoni提供超导膜。这项研究是由欧洲研究理事会资助ERC-2014-STG- 639792支持，居里夫人职业集成格兰特FP7-人2012年CIG-333799，以色列科学基金会资助环球基金系列 – 1102年至1113年。
Materials
| stick slip coarse motion system | attocube | ANPx-101 | x,y motion |
| stick slip coarse motion system | attocube | ANPz-101 | z motion |
| stick slip coarse motion system controller | Attocube | ANC 300 | |
| high voltage amplifier | Attocube | ANC 250 | |
| data acquisition card | National Instruments | NI PCIe-6363 | |
| piezo elements | Piezo Systems Inc | T2C | non magnetic |
| low noise voltage preamplifier | Stanford Research Systems | SR 560 | |
| capacitance bridge | General Radio | 1615A | |
| telescope | NAVITAR | 1-504516 | |
| camera | MOTICAM | MP2 | |
| dewar | Cryofab | N/A | |
| insert | ICE oxford | N/A | |
| Mu-metal shield | Amuneal | N/A | |
| vacuum cap | ICE oxford | N/A | |
| sputtering system | AJA international Inc | N/A | |
| lapping film | 3M | 261X | non magnetic |
| Nb target | Kurt J. Lesker | EJTNBXX351A2 | |
| GE Varnish | CMR-Direct | 02-33-001 | for cryogenic heatsinking |
| Silver paste | Structure Probe Inc | 05063-AB |
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