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TT: Fachverband Tiefe Temperaturen

TT 15: Focus Session: Evolution of Topological Materials into Superconducting Nanodevices (joint session HL/TT)

TT 15.6: Vortrag

Montag, 18. März 2024, 16:15–16:30, EW 202

Van der Pauw measurements for the optimization of magnetic topological insulators — •Jan Karthein^1,3, Jonas Buchhorn^1,3, Kaycee Underwood^1,3, Abdur Reman Jalil^1,3, Peter Schüffelgen^1,3, Detlev Grützmacher^1,2,3, and Thomas Schäpers^1,3 — ¹Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany — ²Peter Grünberg Institut (PGI-10), Forschungszentrum Jülich, 52425 Jülich, Germany — ³JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany

Quantum anomalous Hall insulators are proposed to be a platform for the realization of chiral Majorana edge modes when coupled to a superconductor by the proximity effect. The quantum anomalous Hall state has already been achieved in magnetic topological insulators but inducing superconductivity into these materials remains a challenge. We present a measurement scheme based on the van der Pauw method that allows to get fast insights into the electrical transport properties of thin films at low temperatures prepared by molecular beam epitaxy. On the example of Cr-doped (Bi_xSb_1−x)₂Te₃ the effect of different growth parameters is investigated and compared to Hall bar measurements. The van der Pauw method enables a fast feedback loop between growth and transport measurements. This will help to establish a reliable epitaxial growth of quantum anomalous Hall insulator thin films and allow to systematically search for promising material compositions to induce superconductivity into magnetic topological insulators.

Keywords: Magnetic topological insulators; Quantum anomalous Hall effect; Magneto-transport measurements; Van der Pauw technique; Molecular beam epitaxy