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Title: Exchange bias in polycrystalline magnetite films made by ion-beam assisted deposition

Iron oxide films were produced using ion-beam-assisted deposition, and Raman spectroscopy and x-ray diffraction indicate single-phase magnetite. However, incorporation of significant fractions of argon in the films from ion bombardment is evident from chemical analysis, and Fe/O ratios are lower than expected from pure magnetite, suggesting greater than normal disorder. Low temperature magnetometry and first-order reversal curve measurements show strong exchange bias, which likely arises from defects at grain boundaries, possibly amorphous, creating frustrated spins. Since these samples contain grains ∼6 nm, a large fraction of the material consists of grain boundaries, where spins are highly disordered and reverse independently with external field.
Authors:
;  [1] ;  [2] ; ;  [3] ;  [4] ;  [2] ;  [5]
  1. Department of Physics, University of Idaho, Moscow, Idaho 83844 (United States)
  2. Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
  3. Department of Physics, University of California, Davis, California 95616 (United States)
  4. University of Nebraska Medical Center, Omaha, Nebraska 68198 (United States)
  5. (United States)
Publication Date:
OSTI Identifier:
22308208
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 17; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHEMICAL ANALYSIS; CRYSTAL DEFECTS; DEPOSITION; FILMS; GRAIN BOUNDARIES; ION BEAMS; IRON OXIDES; MAGNETITE; POLYCRYSTALS; RAMAN SPECTROSCOPY; SPIN; X-RAY DIFFRACTION