# Cooling and heating by adiabatic magnetization in the Ni$_{50}$Mn$_{34}$In$_{16}$ magnetic shape memory alloy

## TL;DR

This study investigates the adiabatic temperature changes in Ni50Mn34In16 alloy, revealing both conventional and inverse magnetocaloric effects associated with magnetic and structural transitions, and compares experimental data with thermodynamic predictions.

## Contribution

It provides the first detailed measurement of adiabatic temperature changes in Ni50Mn34In16 alloy, highlighting the effects of first- and second-order transitions on magnetocaloric behavior.

## Key findings

- Conventional magnetocaloric effect heats the alloy near the Curie point.
- Inverse effect causes temperature decrease during martensitic transition.
- Discrepancies at high fields are due to irreversibility of the first-order transition.

## Abstract

We report on measurements of the adiabatic temperature change in the inverse magnetocaloric Ni$_{50}$Mn$_{34}$In$_{16}$ alloy. It is shown that this alloy heats up with the application of a magnetic field around the Curie point due to the conventional magnetocaloric effect. In contrast, the inverse magnetocaloric effect associated with the martensitic transition results in the unusual decrease of temperature by adiabatic magnetization. We also provide magnetization and specific heat data which enable to compare the measured temperature changes to the values indirectly computed from thermodynamic relationships. Good agreement is obtained for the conventional effect at the second-order paramagnetic-ferromagnetic phase transition. However, at the first order structural transition the measured values at high fields are lower than the computed ones. Irreversible thermodynamics arguments are given to show that such a discrepancy is due to the irreversibility of the first-order martensitic transition.