Resistivity and Thermopower of Ni2.19Mn0.81Ga

TL;DR

This study investigates the thermoelectric power and resistivity of Ni2.19Mn0.81Ga, revealing how structural and magnetic transitions influence its electronic properties, with comparisons to the stoichiometric Ni2MnGa.

Contribution

First analysis of thermoelectric power in Ni2.19Mn0.81Ga, linking temperature dependence to crystal field splitting and electronic density of states changes.

Findings

TEP behavior explained by crystal field splitting

Structural transition temperature identified from resistivity

Magnetic and martensitic transitions occur near the same temperature

Abstract

In this paper, we report results of the first studies on the thermoelectric power (TEP) of the magnetic heusler alloy Ni$_{2.19}$Mn$_{0.81}$Ga. We explain the observed temperature dependence of the TEP in terms of the crystal field (CF) splitting and compare the observed behavior to that of the stoichiometric system Ni$_2$MnGa. The resistivity as a function of temperature of the two systems serves to define the structural transition temperature, T$_M$, which is the transition from the high temperature austenitic phase to low temperatures the martensitic phase. Occurrence of magnetic (Curie-Weiss) and the martensitic transition at almost the same temperature in Ni$_{2.19}$Mn$_{0.81}$Ga has been explained from TEP to be due to changes in the density of states (DOS) at the Fermi level.