Electronic band structure and magnetism of CoFeV0.5Mn0.5Si

Parashu Kharel,Paul M Shand,Pavel V Lukashev,Shah Valloppilly,Adam Ramker,Young Moua,Matthew Flesche,Gavin Baker

doi:10.1063/9.0000252

Abstract

Half-metallic Heusler alloys have attracted significant attention due to their potential application in spin-transport-based devices. We have synthesized one such alloy, CoFeV0.5Mn0.5Si, using arc melting and high-vacuum annealing at 600 °C for 24 hours. First principles calculation indicates that CoFeV0.5Mn0.5Si shows a nearly half-metallic band structure with a degree of spin polarization of about 93%. In addition, this value can be enhanced by the application of tensile strain. The room temperature x-ray diffraction patterns are indexed with the cubic crystal structure without secondary phases. The annealed sample shows ferromagnetic order with the Curie temperature well above room temperature (Tc = 657 K) and a saturation magnetization of about 92 emu/g. Our results indicate that CoFeV0.5Mn0.5Si has a potential for room temperature spin-transport-based devices.

Highlights

The degree of spin polarization in electron transport is one of the key parameters taken into account for potential device applications in spin-based electronics.1 In recent years, two types of materials have attracted particular attention for spintronic applications – half-metals and spin-gapless semiconductors (SGS)
We report the results of a combined experimental and theoretical investigation on CoFeV0.5Mn0.5Si, which is nearly half-metallic with an equilibrium spin polarization of about 93%
The energy gap of the minorityspin states of CoFeV0.5Mn0.5Si is reduced as a small number of vanadium states populate the Fermi level

Summary

Introduction

The degree of spin polarization in electron transport is one of the key parameters taken into account for potential device applications in spin-based electronics. In recent years, two types of materials have attracted particular attention for spintronic applications – half-metals and spin-gapless semiconductors (SGS). The degree of spin polarization in electron transport is one of the key parameters taken into account for potential device applications in spin-based electronics.. Two types of materials have attracted particular attention for spintronic applications – half-metals and spin-gapless semiconductors (SGS). Both types of materials can potentially exhibit 100% spin polarization. The degree of spin polarization P is defined as P = (N↑(EF) − N↓(EF))/(N↑(EF) + N↓(EF)), where N↑↓(EF) is the spin-dependent density of states at the Fermi level, EF.. Half-metals are the materials that have a semiconducting or insulating band structure for one spin, and metallic band structure for the opposite spin.. Spin-gapless semiconductors exhibit semiconducting or insulating band structure for one spin, and gapless band structure for the opposite spin.

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