Crossover of magnetoresistance in the zerogap half-metallic Heusler alloy Fe2CoSi

TL;DR

This study investigates the unique electronic and magnetic properties of Fe2CoSi, revealing a crossover in magnetoresistance linked to spin carrier changes, supported by first-principles calculations and experimental measurements.

Contribution

It provides new insights into the spin-dependent transport in Fe2CoSi, highlighting the magnetoresistance crossover related to its peculiar band structure.

Findings

Fe2CoSi has a high Curie temperature of 1038 K.

A temperature-induced crossover from positive to negative MR was observed.

The MR crossover is due to a change in dominant spin carriers at the Fermi level.

Abstract

This work reports on the band structure and magneto-transport investigations of the inverse Heusler compound Fe2CoSi. The first-principles calculations reveal that Fe2CoSi has a very peculiar band structure with a conducting property in the majority spin channel and a nearly zero bandgap in the minority spin channel. The synthesized Fe2CoSi sample shows a high-ordered inverse Heusler structure with a magnetic moment of 4.88 {\mu}B at 5 K and a high Curie temperature of 1038 K. With increasing temperature, a crossover from positive to negative magnetoresistance (MR) is observed. Complemented with the Hall effect measurements, we suggest the intriguing crossover of MR can be ascribed to the dominant spin carriers changing from the gapless minority spin channel to the majority spin channel at Fermi level.