# Evidence for the formation of nanoprecipitates with magnetically disordered regions in bulk $\mathrm{Ni}_{50}\mathrm{Mn}_{45}\mathrm{In}_{5}$ Heusler alloys

## TL;DR

This study reveals the formation of nanoprecipitates with magnetically disordered regions in bulk Ni-Mn-In Heusler alloys, using advanced neutron scattering techniques to analyze their magnetic microstructure and particle sizes.

## Contribution

It provides new insights into the mesoscopic spin structure and nanoprecipitate formation in Ni-Mn-In Heusler alloys through combined magnetometry, synchrotron X-ray diffraction, and SANS analysis.

## Key findings

- Nanoprecipitates with ferromagnetic components form in an antiferromagnetic matrix.
- Disordered regions are associated with particle-matrix interfaces.
- Particle size is approximately 55 nm, with 20 nm spin-canted regions.

## Abstract

Shell ferromagnetism is a new functional property of certain Heusler alloys which has been recently observed in $\mathrm{Ni}_{50}\mathrm{Mn}_{45}\mathrm{In}_{5}$. We report the results of a comparative study of the magnetic microstructure of bulk $\mathrm{Ni}_{50}\mathrm{Mn}_{45}\mathrm{In}_{5}$ Heusler alloys using magnetometry, synchrotron x-ray diffraction, and magnetic small-angle neutron scattering (SANS). By combining unpolarized and spin-polarized SANS (POLARIS) we demonstrate that a number of important conclusions regarding the mesoscopic spin structure can be made. In particular, the analysis of the magnetic neutron data suggests that nanoprecipitates with an effective ferromagnetic component form in an antiferromagnetic matrix on field annealing at $700 \, \mathrm{K}$. These particles represent sources of perturbation, which seem to give rise to magnetically disordered regions in the vicinity of the particle-matrix interface. Analysis of the spin-flip SANS cross section via the computation of the correlation function yields a value of $\sim 55 \, \mathrm{nm}$ for the particle size and $\sim 20 \, \mathrm{nm}$ for the size of the spin-canted region.