Metastability in the Magnetic Structure of Ni51Mn33.4In15.6 Heusler Alloy

The metastability of the nonstoichiometric Ni
₅₁
Mn
_33.4
In
_15.6
Heusler alloy in the first-order transition region is studied using direct adiabatic temperature change (ΔT
_ad
) measurements for heating and cooling magnetization processes. During the heating process, ΔT
_ad
shows an unusual pronounced peak at 294 K in low applied magnetic fields. The height of this peak diminishes and eventually vanishes at higher fields. Kinks are as well observed in the 290-295 K temperature interval for both processes. The existence of the peak and kinks is indicative of the complex magnetic dynamics in Ni
₅₁
Mn
_33.4
In
_15.6
and is attributed to a spin-reorientation transition near the first-order phase transition temperature.