Controllable magnetic anisotropy and ferroelasticity in a superconducting FeSe monolayer with surface fluorine adsorption

Controllable magnetization in atomically thin two-dimensional magnets is\nhighly desirable for developing spintronics. For FeSe monolayer, its magnetic\nground state is not yet fully understood, and the potential in constructing\nhigh-speed and advanced devices remains unknown. Using density functional\ntheory calculations, we confirm the spin ordering of monolayer FeSe to be dimer\ntexture. With Fluorine (F) adsorption (F/FeSe), the system exhibits a coverage\ndependent magnetic anisotropy and multiferroicity which can be attributable to\nthe Jahn-Teller effect, being the benefit to potential spintronic applications.\nIntriguingly, an inherent coupling between magnetism and ferroelasticity in the\nmost energetically favorable F/FeSe system is proposed. Our study thus not only\nprovides a promising way to control the spintronic properties and construct\nmultiferroics, but also renders F/FeSe an ideal platform for magnetism studies\nand practical high-performance multifunctional devices.\n