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Title: Half-metallic magnetism and the search for better spin valves

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 ∼950 K.
Authors:
; ;  [1]
  1. Department of Physics, The University of Texas at Austin, 2515 Speedway, Austin, Texas 78712 (United States)
Publication Date:
OSTI Identifier:
22314345
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; FERMI LEVEL; MAGNESIUM OXIDES; MAGNETIZATION; MAGNETORESISTANCE; OPTIMIZATION; SPIN; SPIN ORIENTATION; SUPERCONDUCTING JUNCTIONS; TEMPERATURE DEPENDENCE; TRANSITION ELEMENTS; TRANSITION TEMPERATURE; TUNNEL EFFECT; YIELDS