Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 8: Topological Insulators I (joint session HL/TT)

TT 8.11: Talk

Monday, March 12, 2018, 12:15–12:30, A 151

Exploiting Topological Insulators for Majorana Devices — •Peter Schüffelgen¹, Daniel Rosenbach¹, Chuan Li², Michael Schleenvoigt¹, Tobias Schmitt¹, Sarah Schmitt¹, Abdur Jalil¹, Jonas Kölzer¹, Lidia Kibkalo¹, Benjamin Bennemann¹, Umut Parlak¹, Martina Luysberg¹, Gregor Mussler¹, Alexander Golubov², Alexander Brinkman², Thomas Schäpers¹, and Detlev Grützmacher¹ — ¹Peter Grünberg Institut, Forschungszentrum Jülich, D-52425 Jülich, Germany — ²MESA+ Institute for Nanotechnology, University of Twente, 7500AE Enschede, The Netherlands

At the interface of s-wave superconductors (SC) and topological insulators (TI) exotic Majorana modes are predicted to occur. In this work, a novel fabrication technique is presented, which allows to construct TI-SC hybrid devices of high quality under ultra-high vacuum conditions. A stencil mask is applied to the substrate before growth of Bi-based TI thin films by means of molecular beam epitaxy. The shadow mask is used for stencil lithography of superconductive electrodes on top of the topological thin film in a second growth step. Measurements on such in-situ fabricated Josephson junctions indicate a high interface transparency. Furthermore, a missing first Shapiro step was detected in radio frequency experiments, indicating signatures of gapless Andreev bound states, so-called Majorana bound states. The presented process is applicable to a variety of new geometries, allowing fabrication of elaborated TI-SC hybrid devices, for further research on Majorana signatures.