Spin Texture Control and Magnetic Gap Engineering in a Ferromagnetic Insulator-Topological Insulator Sandwiched...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Quantum materials integrating magnetism and topological order are crucial for spintronics and low-energy electronics.
• Emergent quantum phenomena like the quantum anomalous Hall effect and axion insulator states are enabled by these materials.

Purpose of the Study:

• To investigate the potential of a specific ferromagnetic insulator (FMI)/topological insulator (TI)/FMI heterostructure for achieving quantum phenomena at higher temperatures.
• To directly verify the origin of the band gap and confirm the mechanism responsible for its opening.

Main Methods:

• Utilized spin- and angle-resolved photoemission spectroscopy (spin-ARPES) for direct observation.
• Employed external magnetic fields to control the spin state.

Main Results:

• Directly verified that the band gap originates from broken time-reversal symmetry due to proximity-driven magnetization.
• Confirmed the exchange interaction as the mechanism responsible for opening the band gap.
• Demonstrated control over the spin state using external magnetic fields.

Conclusions:

• The studied heterostructure exhibits a robust magnetic gap and controllable spin texture.
• This material is a promising candidate for spintronic applications and realizing magnetic topological quantum phases at elevated temperatures.