Direct observation of interfacial exchange coupling in a magnetic tunnel junction through spin-polarized quasiparticle interference

Abstract

Interfacial exchange coupling plays a critical role in enabling novel phenomena in magnetic heterostructures, such as spin triplet superconductivity, quantum anomalous Hall effect (QAHE), and advanced spintronic functionalities. While microscopic characterization of this coupling is essential for elucidating the underlying mechanism, it remains technically challenging. Here, using spin-polarized scanning tunneling microscopy (SP-STM) and quasiparticle interference, we directly observed interfacial exchange coupling in a magnetic tunnel junction formed by an Fe coated tip and a Cr(001) surface. We found the ferromagnetic tip induces significant energy shift (up to 10 meV) in the spin-polarized surface state of Cr(001). This shift is highly sensitive to the tip-surface distance and the spin-alignment between Fe tip and Cr surface, which can be switched by external magnetic field. Our results demonstrate that extended 2D surface states can mediate strong exchange coupling across a heterojunction, enabling local control of interfacial exchange interaction induced phenomena.

References in corpus (19)

• Spintronics: Fundamentals and applications
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Proximity effects in superconductor-ferromagnet heterostructures
• Odd Triplet Superconductivity and Related Phenomena in Superconductor-Ferromagnet Structures
• Prediction and observation of the first antiferromagnetic topological insulator
• Superconducting Spintronics
• Colloquium: Quantum anomalous Hall effect
• Large magnetic gap at the Dirac point in a Mn-induced Bi${}_2$Te${}_3$ heterostructure
• Odd-frequency superconductivity
• Imaging Pauli repulsion in scanning tunneling microscopy
• Surface State Stark Shift in a Scanning Tunneling Microscope
• Giant thermal spin torque assisted magnetic tunnel junction switching
• Stark effect of the Au(111) and Cu(111) surface states
• Real-space Observation of Incommensurate Spin Density Wave and Coexisting Charge Density Wave on Cr(001) surface
• Quantifying Exchange Forces of a Non-Collinear Magnetic Structure on the Atomic Scale
• Site-dependent evolution of electrical conductance from tunneling to atomic point contact
• Relating spin-polarized STM imaging and inelastic neutron scattering in the van-der-Waals ferromagnet Fe3GeTe2
• Discovery of Itinerant Magnetic Domain Wall and Quasiparticle Boundary State in Spin-Density-Waves