Regensburg 2025 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 13: Poster
DS 13.16: Poster
Donnerstag, 20. März 2025, 18:00–20:00, P1
Qauntum anomalous Hall effect in Cr-doped BST — •Edoardo Tosi1,2, Gertjan Lippertz1, Anjana Uday1, Bibek Bhujel1, Alexey Taskin1, Marco Moretti2, and Yoichi Ando1 — 1University of Cologne — 2Polytechnic University of Milan
The quantum anomalous Hall (QAH) effect in a magnetic topological insulator (TI) represents a new state of matter originating from the interplay between topology and magnetism. The defining characteristics of the QAH ground state are the quantized Hall resistivity and vanishing longitudinal resistivity in the absence of an external magnetic field. Manipulating the QAH state is of great importance in both the understanding of topological quantum physics and the implementation of dissipationless electronics.
To observe the QAH effect, fabrications of thin-film devices are required which allows for tuning the Fermi level across the Dirac point. It is necessary to improve growth conditions for the ternary compound (Bi1-xSbx)2Te3 such that the composition between n-type Bi2Te3 and p-type Sb2Te3 can be almost perfectly compensated. Decreasing the thickness of the MBE grown films, reduces the bulk-to-surface ratio and leads to TI samples where the surface transport is dominating. Doping ultrathin films with Cr allows to obtain the ferromagnetic state, which opens a gap in the surface states, leading to the QAH effect at low temperatures.
In this contribution we report our efforts to realize the QAH effect in the magnetic topological insulator Cr-doped (Bi,Sb)2Te3 (CBST) grown by molecular beam epitaxy (MBE) on an InP substrate.
Keywords: quantum anomalous Hall (QAH); topological insulator (TI); magnetic doping