Superconducting Proximity Effect on a Magnetically Doped Topological Insulator Controlled by Magnetization

Proximity effect (PE) on magnetized topological insulators (TIs) has the potential to induce unconventional Cooper pairs, some of which can host Majorana fermions whose antiparticles are themselves. Theory predicts that the magnetized TI systems can tune its PE from a topological to a non-topological state by magnetization and chemical potential.
In this study, we investigated the magnetization dependence of PE on an Nb/ Fe-doped Bi₂Te₂Se Josephson junction. We evaluated I_c-H characteristics before/after applying large magnetic fields. The I_c-H patterns show typical Fraunhofer-like patterns with slight hysteresis. After large magnetic fields (> 0.5 T), the patterns were drastically shift depending on the direction of the last large fields. This shift indicates that the critical currents are sensitive to the existing remnant magnetization. We also observed a transition-like behavior in the conductance spectrum, which may relate with a topological phase transition.