Quantum interference of edge supercurrents in a two-dimensional topological insulator
Quantum interference of edge supercurrents in a two-dimensional topological insulator
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二维拓扑绝缘体中边缘超电流的量子干涉
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
E. Hankiewicz
中科院分区：
文献类型：
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作者：
G. Tkachov;P. Burset;B. Trauzettel;E. Hankiewicz
由二维拓扑绝缘体（TI）制成的约瑟夫森弱连接表现出超导量子干涉器件（SQUID）中的超导电流磁振荡。我们提出了一个微观理论的这种效果，超越了基于标准SQUID理论的方法。对于长结，我们发现了一个温度驱动的交叉从Phi_0周期SQUID类振荡到2 Phi_0准周期干涉图案与不同的峰值在偶数和奇数值的磁通量子Phi_0=ch/2 e。在短结中不存在这种行为，在短结中，主要干扰信号发生在零磁场处。这两种类型的干涉图案揭示了无间隙（保护）Andreev束缚态。然而，我们发现，通常的超导电流通量的关系是深刻修改的多普勒效应的屏蔽电流，这已被忽视以前。我们的研究结果可以解释最近观察到的偶奇干涉图案在InAs/GaSb基TI约瑟夫森结和发现未开发的操作制度的纳米SQUID。
Josephson weak links made of two-dimensional topological insulators (TIs) exhibit magnetic oscillations of the supercurrent that are reminiscent of those in superconducting quantum interference devices (SQUIDs). We propose a microscopic theory of this effect that goes beyond the approaches based on the standard SQUID theory. For long junctions we find a temperature-driven crossover from Phi_0-periodic SQUID-like oscillations to a 2 Phi_0-quasiperiodic interference pattern with different peaks at even and odd values of the magnetic flux quantum Phi_0=ch/2e. This behavior is absent in short junctions where the main interference signal occurs at zero magnetic field. Both types of interference patterns reveal gapless (protected) Andreev bound states. We show, however, that the usual sawtooth current-flux relationship is profoundly modified by a Doppler-like effect of the shielding current which has been overlooked previously. Our findings may explain recently observed even-odd interference patterns in InAs/GaSb-based TI Josephson junctions and uncover unexplored operation regimes of nano-SQUIDs.