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arXiv · 1407.5240

Half-metallic magnetism and the search for better spin valves

Karin Everschor-Sitte·Matthias Sitte·Allan H. MacDonald
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Abstract

We use a previously proposed theory for the temperature dependence of tunneling magnetoresistance to shed light on ongoing efforts to optimize spin valves. First we show that a mechanism in which spin valve performance at finite temperatures is limited by uncorrelated thermal fluctuations of magnetization orientations on opposite sides of a tunnel junction is in good agreement with recent studies of the temperature-dependent magnetoresistance of high quality tunnel junctions with MgO barriers. Using this insight, we propose a simple formula which captures the advantages for spin-valve optimization of using materials with a high spin polarization of Fermi-level tunneling electrons, and of using materials with high ferromagnetic transition temperatures. We conclude that half-metallic ferromagnets can yield better spin-value performance than current elemental transition metal ferromagnet/MgO systems only if their ferromagnetic transition temperatures exceed $\sim 950~\mathrm{K}$.

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Karin Everschor-Sitte, Matthias Sitte, Allan H. MacDonald. 2014-07-20. Half-metallic magnetism and the search for better spin valves. https://doi.org/10.1063/1.4893969

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