Engineering Epitaxial Interfaces for Topological Insulator — Superconductor Hybrid Devices with Al Electrodes

IF 4.4 Q1 OPTICS
Abdur Rehman Jalil, Tobias W. Schmitt, Philipp Rüßmann, Xian-Kui Wei, Benedikt Frohn, Michael Schleenvoigt, Wilhelm Wittl, Xiao Hou, Anne Schmidt, Kaycee Underwood, Gustav Bihlmayer, Martina Luysberg, Joachim Mayer, Stefan Blügel, Detlev Grützmacher, Peter Schüffelgen
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Abstract

Proximity-induced superconductivity in hybrid devices of topological insulators and superconductors offers a promising platform for the pursuit of elusive topological superconductivity and its anticipated applications, such as fault-tolerant quantum computing. To study and harness such hybrid devices, a key challenge is the realization of highly functional material interfaces with a suitable superconductor featuring 2 e $e$ -periodic parity-conserving transport to ensure a superconducting hard-gap free of unpaired electrons, which is important for Majorana physics. A superconductor well-known for this characteristic is Al, however, its direct integration into devices based on tetradymite topological insulators has so far been found to yield non-transparent interfaces. By focusing on Bi2Te3-Al heterostructures, this study identifies detrimental interdiffusion processes at the interface through atomically resolved structural and chemical analysis, and showcases their mitigation by leveraging different interlayers – namely Nb, Ti, Pd, and Pt – between Bi2Te3 and Al. Through structural transformation of the interlayer materials (X) into their respective tellurides (XTe2) atomically-sharp epitaxial interfaces are engineered and further characterized in low-temperature transport experiments on Al-X-Bi2Te3-X-Al Josephson junctions and in complementary density functional theory calculations. By demonstrating functional interfaces between Bi2Te3 and Al, this work provides key insights and paves the way for the next generation of sophisticated topological devices.

Abstract Image

铝电极拓扑绝缘体-超导体混合器件的工程外延界面
拓扑绝缘体和超导体混合器件中的邻近诱导超导性为追求难以捉摸的拓扑超导性及其预期应用(如容错量子计算)提供了一个有前途的平台。为了研究和利用这种混合器件,一个关键的挑战是实现高功能的材料界面,使用具有2 e$ e$ -周期宇称守恒输运的合适超导体,以确保超导硬隙中没有未配对电子,这对马约拉纳物理学很重要。以这一特性而闻名的超导体是Al,然而,迄今为止,人们发现将其直接集成到基于四矿拓扑绝缘体的器件中会产生不透明的界面。通过关注Bi2Te3-Al异质结构,本研究通过原子解析结构和化学分析确定了界面上有害的相互扩散过程,并展示了通过利用不同的中间层-即Nb, Ti, Pd,在Al-X-Bi2Te3-X-Al Josephson结的低温输运实验和互补密度泛函理论计算中,通过层间材料(X)向各自的碲化物(XTe2)的结构转变,设计并进一步表征了原子尖锐外延界面。通过展示Bi2Te3和ai之间的功能接口,这项工作提供了关键的见解,并为下一代复杂的拓扑器件铺平了道路。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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CiteScore
7.90
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