Room-Temperature Magnetic Bistability in Epitaxial Fe_0.52Rh_0.48/MgO(001) Film Grown by Molecular Beam Epitaxy and Its Application in Rewritable Magnetic Patterning

Iron rhodium (FeRh) goes through an entropy-driven first-order transition from an antiferromagnetic state to a ferromagnetic state as temperature increases. The rhodium fraction x in Fe_1-xRh_x has a profound effect on its structure, transport characteristics and magnetic properties. By utilizing molecular beam epitaxy as a tool to controllably tune the chemical composition of Fe_1-xRh_x thin films, we have systematically investigated the magnetic transition as a function of x. Rhodium deficient films have a lower transition temperature T_c compared to stoichiometric film. At x=0.48, we demonstrate a room-temperature bistability in this alloy, where Fe_0.52Rh_0.48 is ferromagnetic at high temperatures down to ~280 K and antiferromagnetic at low temperatures up to ~350 K. The width of the thermal hysteresis is sufficiently narrow to enable efficient controllability, but also wide enough to robustly withstand thermal perturbations. Based on this bistability, we demonstrate the use of local laser heating to write arbitrary patterns of the ferromagnetic phase that are also erasable.

Adv. Mater. 32, 2001080 (2020)
Appl. Phys. Lett. 113, 082403 (2018)