Multiple first order transitions and associated room temperature magneto-functionality in Ni2.048Mn1.312In0.64

TL;DR

This study reports multiple first-order magnetic transitions in a Ni-rich alloy, exhibiting room temperature magneto-functionalities like large magnetoresistance and magnetocaloric effects, linked to distinct phase transitions.

Contribution

It demonstrates the coexistence of multiple first-order magnetic transitions and associated functional properties in a Ni-based shape memory alloy at near room temperature.

Findings

Observation of two distinct magnetic phase transitions with thermal hysteresis.

Confirmation of first-order nature through Arrott plot analysis.

Large magnetoresistance and magnetocaloric effects near transition temperatures.

Abstract

Present work reports on the observation of multiple magnetic transitions in a Ni-excess ferromagnetic shape memory alloy with nominal composition Ni$_{2.048}$Mn$_{1.312}$In$_{0.64}$. The magnetization data reveal two distinct thermal hystereses associated with two different phase transitions at different temperature regions. The high temperature magnetic hysteresis is due to the martensitic phase transition whereas the low temperature hysteresis occurs around the magnetic anomaly signifying the transition from a paramagnetic-like state to the ferromagetic ground state within the martensite. Clear thermal hysteresis along with the sign of the curvatures of Arrott plot curves confirm the {\it first order nature of both the transitions}. In addition, the studied alloy is found to be functionally rich with the observation of large magnetoresistance (-45\% and -4\% at 80 kOe) and magnetocaloric effect (+16.7 J.kg$^{-1}$.K$^{-1}$ and -2.25 J.kg$^{-1}$.K$^{-1}$ at 50 kOe) around these two hysteresis regions (300 K and 195 K respectively).