Regensburg 2022 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 36: Materials and Devices for Quantum Technology 2

HL 36.6: Talk

Thursday, September 8, 2022, 16:30–16:45, H36

Searching for signatures of magnetism and induced superconductivity in magnetic topological insulator-superconductor hybrid devices — •Max Vaßen-Carl, Michael Schleenvoigt, Benedikt Frohn, Detlev Grützmacher, and Peter Schüffelgen — Peter Grünberg Institute 9, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

Topological materials harbor great possibilities for the future of quantum computation. In theory, when quasi-1D topological isolators (TIs) are coupled to superconductors localized Majorana zero modes (MZM) arise at the end of the quasi-1D hybrid structure. However, quasi-1D TIs require a certain in-plane magnetic field, which depends on the cross-section area of the TI, to retrieve the topological properties lost by confinement. Deviations of said TI cross-section change the penetrating flux and can lead to additional opening and closing of the topological gap, creating unwanted MZMs. One possible solution is to integrate magnetism directly into the TI, creating so-called magnetic topological insulators (MTIs), which retain their topological properties even when confined. In this work Chromium is used to magnetically dope (BixSb1-x)2Te3, by means of MBE. First, ex-situ fabricated MTI-Nb Josephson Junctions (JJ) showed no supercurrent, but instead an increase of resistance for low bias voltages. To gain further insights on the interplay between SC and MTI a new sample layout was designed which allows for Josephson and Hall bar measurements in one device. In order to obtain highest S-MTI interface quality those hybrid devices are fully fabricated under UHV conditions.