Interfacial Coexistence of Superconductivity and Magnetism in NbN/Ti/MnBi ₂ Te ₄ Heterostructures

Magnetic/superconducting heterostructures represent a frontier in condensed matter physics, offering pathways to realize unconventional pairing mechanisms such as topological superconductivity, spin-triplet pairing, and Majorana zero modes for fault-tolerant quantum computing. In this work, we integrate the magnetic van der Waals material MnBi₂Te₄ (MBT) with a superconducting NbN thin film, achieving ultralow-disorder interfaces through Ti buffer layer engineering. Temperature- and field-dependent critical currents, extracted from differential resistance spectra, reveal robust coupling between the MnBi₂Te₄ and the superconducting order of NbN, enabling proximity-induced superconductivity within MnBi₂Te₄. Notably, the proximity-induced critical currents remain invariant under in-plane field rotation, in contrast to the anisotropic response observed in pristine NbN. Moreover, the hysteretic behavior observed in the interfacial magnetoresistance curves confirms the proximity-induced spin polarization at the MBT interface, which is consistent with Andreev reflection results. These findings demonstrate a platform for fabricating high-quality heterointerfaces and enable targeted exploration of exotic quantum states.