CoFeVSb: A Promising Candidate for Spin Valve and Thermoelectric Applications

TL;DR

This study combines theoretical and experimental approaches to demonstrate that CoFeVSb, a quaternary Heusler compound, exhibits promising spintronic and thermoelectric properties at room temperature, including half-metallicity, spin-valve behavior, and high thermoelectric efficiency.

Contribution

It is the first comprehensive investigation of CoFeVSb showing its potential for spintronics and thermoelectric applications, highlighting the effects of disorder and magnetic interfaces.

Findings

Exhibits room temperature spin-valve behavior stable at 300 K.

Shows high thermoelectric power factor and low thermal conductivity.

Displays half-metallic nature and significant Berry phase contribution.

Abstract

We report a combined theoretical and experimental study of a novel quaternary Heusler system CoFeVSb from the view point of room temperature spintronics and thermoelectric applications. It crystallizes in cubic structure with small DO$_3$-type disorder. The presence of disorder is confirmed by room temperature synchrotron X-ray diffraction(XRD) and extended X-ray absorption fine structure (EXAFS) measurements. Magnetization data reveal high ordering temperature with a saturation magnetization of 2.2 $\mu_B$/f.u. Resistivity measurements reflect half-metallic nature. Double hysteresis loop along with asymmetry in the magnetoresistance(MR) data reveals room temperature spin-valve feature, which remains stable even at 300 K. Hall measurements show anomalous behavior with significant contribution from intrinsic Berry phase. This compound also large room temperature power factor ($\sim0.62$ mWatt/m/K$^{2}$) and ultra low lattice thermal conductivity ($\sim0.4$ W/m/K), making it a promising candidate for thermoelectric application. Ab-initio calculations suggest weak half-metallic behavior and reduced magnetization (in agreement with experiment) in presence of DO$_3$ disorder. We have also found an energetically competing ferromagnetic FM)/antiferromagnetic (AFM) interface structure within an otherwise FM matrix: one of the prerequisites for spin valve behavior. Coexistence of so many promising features in a single system is rare, and hence CoFeVSb gives a fertile platform to explore numerous applications in future.