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arXiv 1805.09574cond-mat.supr-concond-mat.mes-hallcond-mat.str-el
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绝缘态氧化物界面的涡旋激发

Vortex excitations in the Insulating State of an Oxide Interface

M. Mograbi, E. Maniv, P. K. Rout, D. Graf, J. -H Park, Y. Dagan

摘要:

在二维(2D)超导体中,可以通过施加磁场$H$或增加无序来诱导绝缘状态。超导体到绝缘体的转变(SIT)有多种解释:库珀对断裂后的费米物理、嵌入金属或绝缘基体中的超导岛之间的相位相干性丧失以及库珀对的局域化伴随涡旋型激发的凝聚。表征绝缘状态及其起源的困难源于缺乏单个样品中超导到绝缘相图的连续映射。本文利用在两个绝缘体(111)SrTiO $_3$和LaAlO $_3$之间的界面处形成的二维电子液体来研究超导体到绝缘体的转变。该结晶界面令人惊讶地表现出以前仅在无定形体系中观察到的非常强的特征。通过使用静电门控和磁场,将样品从金属区域(其中超导电性完全显现)调谐到绝缘状态。通过检查的方块电阻的字段依赖性和在不同的方向,我们确定了一个新的磁场规模,H $_{pairing}$,超导波动静音的响应比较。我们的研究结果表明,涡波动激发和库珀对本地化负责所观察到的SIT,这些激发令人惊讶地坚持深入到绝缘状态。

英文摘要:

In two-dimensional (2D) superconductors an insulating state can be induced either by applying a magnetic field, $H$, or by increasing disorder. Many scenarios have been put forth to explain the superconductor to insulator transition (SIT): dominating fermionic physics after the breaking of Cooper pairs, loss of phase coherence between superconducting islands embedded in a metallic or insulating matrix and localization of Cooper pairs with concomitant condensation of vortex-type excitations. The difficulty in characterizing the insulating state and its origin stems from the lack of a continuous mapping of the superconducting to insulating phase diagram in a single sample. Here we use the two-dimensional (2D) electron liquid formed at the interface between the two insulators (111) SrTiO$_3$ and LaAlO$_3$ to study the superconductor to insulator transition. This crystalline interface surprisingly exhibits very strong features previously observed only in amorphous systems. By use of electrostatic gating and magnetic fields, the sample is tuned from the metallic region, where supeconductivity is fully manifested, deep into the insulating state. Through examination of the field dependence of the sheet resistance and comparison of the response to fields in different orientations we identify a new magnetic field scale, H$_{pairing}$, where superconducting fluctuations are muted. Our findings show that vortex fluctuations excitations and Cooper pair localization are responsible for the observed SIT and that these excitations surprisingly persist deep into the insulating state.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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