Proximity Magnetism in Mn(Bi,Sb)2Te4-(Bi,Sb)2Te3/MnTe Natural Heterostructures

Abstract

Magnetic topological insulators and their heterostructures provide great opportunities in coupling band topology with nontrivial spin configuration for enhanced spintronic device performance as well as designing totally new magnetoelectric systems and functionalities. We find that Mn interdiffusion from MnTe when interfaced with (Bi,Sb)2Te3 stabilizes as self-organized Mn(Bi,Sb)2Te4 septuple lamellae amongst alternating (Bi,Sb)2Te3 quintuple layers, as observed using scanning transmission electron microscopy and depth-sensitive polarized neutron reflectometry. We further demonstrate a valuable combination of magnetic and topological orders in these naturally formed Mn(Bi,Sb)2Te4-(Bi,Sb)2Te3 heterostructures that are exchange coupled with MnTe. Magnetotransport experiments and quantum magnetism simulations reveal that, above its own Neel temperature TN of 20 K, Mn(Bi,Sb)2Te4 mediates the exchange field leading to an anomalous Hall effect at the (Bi,Sb)2Te3/MnTe interface, with an enhanced interfacial TN exceeding 200 K. This novel magnetic interface in turn allows a robust and deterministic spin-orbit torque switching without an external magnetic field at a low critical current density of 300 kA cm-2. The antiferromagnetically coupled architecture of Mn(Bi,Sb)2Te4-(Bi,Sb)2Te3/MnTe, featuring unique magnetic and topological proximity effects across a chalcogenide backbone, is rich in fundamental interface physics and holds potential for practical applications in spintronics.

References in corpus (10)

• Colloquium: Quantum anomalous Hall effect
• Progress and prospects in magnetic topological materials
• Observation of high-temperature quantum anomalous Hall regime in intrinsic MnBi${}_2$Te${}_4$/Bi${}_2$Te${}_3$ superlattice
• Tailoring Hybrid Anomalous Hall Response in Engineered Magnetic Topological Insulator Heterostructures
• Progress and prospects in the quantum anomalous Hall effect
• Antiferromagnetic $\alpha$-MnTe: Molten-Salt-Assisted Chemical Vapor Deposition Growth and Magneto-Transport Properties
• Nonreciprocal transport in a bilayer of MnBi2Te4 and Pt
• Antiferromagnetic VdW Phase at the Interface of Sputtered Topological Insulator/Ferromagnet-Bi2Te3/Ni80Fe20 Heterostructures
• Non-Altermagnetic Origin of Exchange Bias Behaviors in Incoherent RuO${}_2$/Fe Bilayer Heterostructures
• Origin of perpendicular magnetic anisotropy in ultra-thin metal films studied by in-situ neutron reflectometry