Restoring the Surface Magnetic Gap in MnBi 2 Te 4
The surface magnetic gap in MnBi2Te4 can be restored by tuning its surface electrostatic potential using external electric fields or interfacial fields. Surface defects initially lower this potential, driving topological states into subsurface layers and closing the gap. Applying an appropriate electric field, either externally or via van der Waals heterostructures, raises the potential to restore the magnetic gap and control its topology.