Interface-Induced Superconductivity in MnBi₂Te₄/FeTe Heterostructures

The interface of two materials can and has been shown to give rise to completely unexpected emergent phenomena, such as interface-induced superconductivity. Moreover, when one of the two materials has a strong spin-orbit coupling, this interface-induced superconductivity may host the topological superconducting phase. In this work, we use molecular beam epitaxy (MBE) to synthesize the MnBi₂Te₄/FeTe heterostructures. MnBi₂Te₄, a tetradymite-type compound, was recently predicted and experimentally demonstrated to be a topological insulator with intrinsic antiferromagnetism and extremely strong spin-orbit coupling. FeTe is also an antiferromagnetic material and non-superconducting. By performing high-resolution scanning transmission electron microscopy measurements, we observe an atomically sharp interface across the septuple-layer structure of MnBi₂Te₄ and the trilayer structure of FeTe. Moreover, our transport measurements uncover a sharp superconducting transition with a zero resistance T_c ~9.3 K. The nonzero anomalous Hall traces appear at temperatures greater than T_c and persist up to ~24 K. The latter value is consistent with the Néel temperature of our MBE-grown MnBi₂Te₄ films. Our successful synthesis of MnBi₂Te₄/FeTe heterostructures with atomically sharp interfaces will advance the fundamental inquiries into the topological superconducting phase in hybrid devices and may provide an alternative approach for the exploration of the topological superconducting phase.