The zero-moment half metal: How could it change spin electronics?

Davide Betto,J M D Coey,Naganivetha Thiyagarajah,Yong-Chang Lau,Karsten Rode,Gwenael Atcheson,Kiril Borisov,Plamen Stamenov,Mario Žic,Thomas Archer

doi:10.1063/1.4943756

Davide Betto, J M D Coey + Show 8 more

Open Access

https://doi.org/10.1063/1.4943756

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Journal: AIP Advances	Publication Date: Mar 7, 2016
Citations: 23	License type: CC BY 3.0

Affiliation: Trinity College Dublin

Abstract

The Heusler compound Mn2RuxGa (MRG) may well be the first compensated half metal. Here, the structural, magnetic and transport properties of thin films of MRG are discussed. There is evidence of half-metallicity up to x = 0.7, and compensation of the two Mn sublattice moments is observed at specific compositions and temperatures, leading to a zero-moment half metal. There are potential benefits for using such films with perpendicular anisotropy for spin-torque magnetic tunnel junctions and oscillators, such as low critical current, high tunnel magnetoresistance ratio, insensitivity to external fields and resonance frequency in the THz range.

Highlights

Half metals are ideal ferromagnets with a spin gap in the majority or minority density of states.[1,2] As a consequence, they exhibit a spin moment per stoichiometric formula unit that is an integral number of Bohr magnetons
The conduction electrons are perfectly spin polarized. Such an ideal material is obviously of interest for spin electronics,[3] where high spin polarization is associated with large magnetoresistance in sensors and memory elements and with a high spin transfer torque efficiency in magnetic switches and oscillators
The study of MRG far has revealed some characteristic features of compensated ferrimagnetic thin films, namely the divergence of the anisotropy field and hysteresis at the compensation point, when the films have some perpendicular anisotropy to begin with

Summary

INTRODUCTION

Half metals are ideal ferromagnets with a spin gap in the majority or minority density of states.[1,2] As a consequence, they exhibit a spin moment per stoichiometric formula unit that is an integral number of Bohr magnetons. It has been difficult to obtain compelling experimental evidence for half-metallicity, especially with surface-sensitive measurements.[2] the possible combination of high spin polarization and zero magnetization is a tantalizing one, which is well worth exploring, both practically and imaginatively.

GROWTH AND STRUCTURE

MAGNETIC AND ELECTRONIC PROPERTIES

CONCLUSIONS