# Local Photothermal Control of Phase Transitions for On-demand Room-temperature Rewritable Magnetic Patterning

## TL;DR

This paper introduces a room-temperature, rewritable magnetic patterning technique using local photothermal control of phase transitions in FeRh thin films, enabling on-demand creation and erasure of magnetic structures.

## Contribution

It presents a novel method for magnetic patterning that allows repeated writing and erasing of arbitrary shapes via laser heating and cooling in bistable FeRh films.

## Key findings

- Successful local laser heating induces ferromagnetic patterns.
- Patterns can be erased by cooling, enabling reusability.
- Demonstrated on arbitrary shapes with room-temperature operation.

## Abstract

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, we report a novel approach for magnetic patterning that allows repeated creation and erasure of arbitrary shapes of thin-film ferromagnetic structures. 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, we demonstrate the ability to write arbitrary patterns of the ferromagnetic phase by local heating with a focused laser. If desired, the results can then be erased by cooling with a thermoelectric cooler and the material repeatedly re-patterned.