Atomic disorder induced modification of magnetization in MnCrVAl

Juliana Herran,Pavel V Lukashev,Paul Gray,Parashu Kharel,Rishabh Dalal

doi:10.1063/1.4998308

Juliana Herran, Pavel V Lukashev + Show 3 more

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https://doi.org/10.1063/1.4998308

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Abstract

We have investigated the physical mechanism behind magnetization reduction in a potential spin-gapless semiconducting compound MnCrVAl by analyzing various atomic disorder schemes. In particular, we show that depending on the degree of disorder, exchanging atomic positions between Mn/Cr and V/Al leads to reduced total magnetization due to either spin flip, or vanishing spin magnetic moments. The latter is attributed to the itinerant character of magnetism in Cr-, Mn-, and V-containing Heusler alloys, and to the frustration of antiferromagnetic exchange interactions, and is accompanied by a tetragonal distortion, but such distortion alone (i.e., in a fully ordered crystal, with no atomic disorder) is not sufficient for a transition to zero magnetization. Besides, we demonstrate that in certain disordered structures the spin polarization of MnCrVAl significantly increases, reaching the half-metallic state. Our calculations indicate that exchange of atomic positions of Mn with Cr, and V with Al has no significant effect on electronic and magnetic properties of MnCrVAl. We also show that antisite disorder does not result in significant reduction of magnetization. At the same time, some types of antisite disorder result in essentially 100% spin-polarized structures. These findings may contribute to understanding the role of atomic disorder on magnetic properties of materials with potential applications in spin-based electronics.

Highlights

Research on magnetic materials for potential applications in spin-based electronics is one of the most active fields of current study in both academia and industry.1–6 In particular, magnetic materials which can produce highly spin polarized current attracted enormous attention
We have investigated the physical mechanism behind magnetization reduction in a potential spingapless semiconducting compound MnCrVAl by analyzing various atomic disorder schemes
We show that depending on the degree of disorder, exchanging atomic positions between Mn/Cr and V/Al leads to reduced total magnetization due to either spin flip, or vanishing spin magnetic moments

Summary

Introduction

Research on magnetic materials for potential applications in spin-based electronics is one of the most active fields of current study in both academia and industry. In particular, magnetic materials which can produce highly spin polarized current (ideally, of only one spin orientation, in which case they are called half-metals) attracted enormous attention. Research on magnetic materials for potential applications in spin-based electronics is one of the most active fields of current study in both academia and industry.. Magnetic materials which can produce highly spin polarized current (ideally, of only one spin orientation, in which case they are called half-metals) attracted enormous attention. Many compounds exhibiting high degree of transport spin polarization have been proposed.. There are various mechanisms which could potentially alter the degree of transport spin polarization, such as mechanical strain, structural disorder, temperature, termination surface/interface in thin film multilayer geometry, etc. It has been shown that segregation of atoms to the surface and emergence of surface states in thin film geometry produce detrimental effects on half-metallic properties.

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