Josephson coupling across magnetic topological insulator MnBi2Te4

Abstract

Topological superconductors hosting Majorana zero modes are of great interest for both fundamental physics and potential quantum computing applications. In this work, we investigate the transport properties of the intrinsic magnetic topological insulator MnBi2Te4 (MBT). In normal transport measurements, we observe the presence of chiral edge channels, though with deviations from perfect quantization due to factors such as non-uniform thickness, domain structures, and the presence of quasi-helical edge states. Subsequently, we fabricate superconducting junctions using niobium leads on MBT exfoliated flakes, which show an onset of supercurrent with clear Josephson coupling. The interference patterns in the superconducting junctions reveal interesting asymmetries, suggesting changes in the magnetic ordering of the MBT flakes under small applied magnetic fields. Moreover, the modulation of the critical current by magnetic field reveals a SQUID-like pattern, suggesting the presence of supercurrent through the quasi-helical edge states.