Preserving Metamagnetism in Self-Assembled FeRh Nanomagnets

TL;DR

This study demonstrates that self-assembled FeRh nanomagnets retain their metamagnetic properties when formed via solid-state dewetting, with their magnetic behavior influenced by nanoisland shape, size, and surface facets.

Contribution

It introduces a scalable self-assembly method using solid-state dewetting to preserve metamagnetism in FeRh nanomagnets, highlighting the role of crystal faceting and geometry.

Findings

Metamagnetism is preserved in nanomagnet arrays formed by dewetting.

Surface facet configurations determine the suppression or preservation of metamagnetism.

Supported nanomagnets exhibit pronounced supercooling and no phase separation.

Abstract

We present self-assembly routes of metamagnetic FeRh nanoisland arrays using sputter deposition processing. Controlling the growth parameters and epitaxy allows tuning the size and shape of the FeRh nanoislands. While the phase transition between antiferromagnetic and ferromagnetic order is largely suppressed in nanoislands formed on oxide substrates via thermodynamic nucleation, we find that metamagnetism is largely preserved in nanomagnet arrays formed through solid-state dewetting. This behavior is strongly dependent on the resulting crystal faceting of the nanoislands, which is characteristic of each assembly route. Comparing the calculated surface energies for each magnetic phase of the nanoislands reveals that metamagnetism can be suppressed or allowed by specific geometrical configurations of the facets. Furthermore, we find that the spatial confinement leads to very pronounced supercooling and the absence of phase separation in the nanoislands. Finally, the supported nanomagnets are chemically etched away from the substrates to inspect the phase transition properties of self-standing nanoparticles. We demonstrate that solid-state dewetting is a feasible and scalable way to obtain supported and free-standing FeRh nanomagnets with preserved metamagnetism.