Composition dependence of magnetoresistance in Fe$_{1-x}$Ni$_{x}$ alloys

TL;DR

This study investigates how the magnetoresistance in Fe-Ni alloys varies with composition and temperature, revealing different scattering mechanisms and sign changes in MR across compositions.

Contribution

It provides detailed measurements of magnetoresistance across multiple compositions and temperatures, highlighting composition-dependent scattering and MR sign changes.

Findings

Resistivity mainly due to electron-phonon or electron-magnon scattering depending on composition.

Magnetoresistance sign changes with temperature for certain compositions.

Linear MR behavior observed in specific alloys.

Abstract

Resistance of Fe$_{1-x}$Ni$_x$(x=0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 0.9) has been measured using four probe method from 5K to 300K with and without a longitudinal magnetic field of 8T. The zero field resistivity of x=0.1 and 0.9 alloys, predominant contribution to resistivity above near room temperature is due to electron-phonon scattering, whereas for x=05 and 0.7 alloys electron-magnon scattering is dominant. Alloys with x=0.1 and 0.9 exhibit positive magnetoresistance(MR) from 5K to 300K. For x=0.5 and 0.7 alloys, magnetoresistance changes sign from positive to negative with increase in temperature. The temperature at which sign changes increase with Ni concentration in the alloy. The field dependent magnetoresistance is positive for x=0.1, 0.7 and 0.9 alloys whereas it is negative for x=0.5 alloy. MR follows linear behaviour with field for x=0.1 alloy. MR of all other alloys follow a second order polynomial in field.