Strain-induced electronic state modulation in epitaxial Bi(110) on two-dimensional ferromagnet Fe<sub>3</sub>GeTe<sub>2</sub>

Precise control of lattice strain and buckling geometry at the nanoscale enables deterministic manipulation of the electronic properties of quantum materials. Low dimensional Bi(110) possesses topological properties and ferroelectricity, which are strongly tied to its atomic structure. Here, by fabricating an epitaxial heterostructure composed of 2−3 bilayer Bi(110) in black phosphorus (BP) structure and Fe3GeTe2 with hexagonal lattice structure, heterostrain and periodical variation of buckling height h are introduced into Bi(110) via interlayer interactions. Modulation of the electronic states and bandgap of ultra-thin Bi(110) are revealed the study of scanning tunneling microscopy and spectroscopy. The regulation of the electronic properties of Bi(110) by lattice stress and magnetic proximity effect of Fe3GeTe2 substrate are further explained by density functional theory calculations. The atomic scale straintronics method offers a strategy to modify the electronic properties of ultra-thin epitaxial films with potential applications in spintronics and nanoelectronics.