Local Photothermal Control of Phase Transitions for On-Demand Room-Temperature Rewritable Magnetic Patterning

The ability to make controlled patterns of magnetic structures within a nonmagnetic background is essential for several types of existing and proposed technologies. Such patterns provide the foundation of magnetic memory and logic devices, allow the creation of artificial spin-ice lattices, and enable the study of magnon propagation. Here, a novel approach for magnetic patterning that allows repeated creation and erasure of arbitrary shapes of thin-film ferromagnetic structures is reported. This strategy is enabled by epitaxial Fe_0.52 Rh_0.48 thin films designed so that both ferromagnetic and antiferromagnetic phases are bistable at room temperature. Starting with the film in a uniform antiferromagnetic state, the ability to write arbitrary patterns of the ferromagnetic phase is demonstrated by local heating with a focused laser. If desired, the results can then be erased by cooling below room temperature and the material repeatedly re-patterned.