# Controlling Magnetic-Field-Induced Shape Memory Response in Polycrystalline Off-Stoichiometry Fe47‑xMn24+xGa29 Microwires

## TL;DR

This study explores how adjusting the composition of Fe–Mn–Ga microwires affects their magnetic shape memory behavior, enabling precise control for potential use in magnetic actuation and sensing.

## Contribution

The paper introduces a composition-driven strategy to tune magnetic-field-induced shape memory effects in Fe–Mn–Ga microwires.

## Key findings

- Fe45Mn26Ga29 microwires show a large thermal hysteresis width of 98 K due to Fe and Mn atom motion.
- An antiferromagnetic transition shifts from 22 to 41 K depending on composition, linked to Fe and Mn 3d orbital interactions.

## Abstract

The ferromagnetic shape memory (FSM) behavior of glass-coated
Fe47‑x
Mn24+x
Ga29 (x = 0–8 at. %) microwires has been
investigated
through temperature-dependent magnetization and ac magnetic susceptibility measurements. Magnetization measurements
as a function of temperature reveal an abrupt increase and decrease
in magnetization upon cooling and heating, respectively, indicating
characteristic thermal hysteresis (ΔT

hys
) behavior typically associated with a magnetic-field-induced
“diffusionless” martensitic transformation. The magnitude
and width of ΔT

hys
are strongly correlated with the Fe/Mn atomic ratio; notably, the
Fe45Mn26Ga29 microwire exhibits a
very large ΔT

hys
width of 98 K, which is attributed to local deformation involving
the motion of Fe and Mn atoms. Furthermore, an antiferromagnetic transition
is observed in a low-temperature region, shifting from 22 to 41 K
depending on composition. This shift is attributed to variations in
local exchange interactions arising from unequal occupation of Fe
and Mn 3d orbitals. These findings highlight a compositionally
driven design strategy that enables precise tuning of FSM behavior,
making Fe–Mn–Ga microwires promising candidates for
use in tunable magnetic actuation and sensing technologies.