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

Iron oxide films were deposited onto Si substrates using ion-beam-assisted deposition. The films were ~300 nm thick polycrystalline magnetite with an average crystallite size of ~6 nm. Additionally, 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. However, Raman spectroscopy and x-ray diffraction both indicate that the films are single-phase magnetite. Since no direct evidence of a second phase could be found, exchange bias likely arises due to defects at grain boundaries, possibly amorphous, creating frustrated spins. Since these samples have such small grains, a large fraction of the material consists of grain boundaries, where spins are highly disordered and reverse independently with external field. Furthermore, the high energy deposition process results in an oxygen-rich, argon-containing magnetite film with low temperature exchange bias due to defects at the high concentration of grain boundaries.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ; ORCiD logo [3] ;  [4] ; ORCiD logo [5]
  1. Univ. of Idaho, Moscow, ID (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Univ. of California, Davis, CA (United States)
  4. Univ. of Nebraska Medical Center, Omaha, NE (United States)
  5. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Washington State Univ., Pullman, WA (United States)
Publication Date:
Report Number(s):
PNNL-SA-104251
Journal ID: ISSN 0021-8979; 44713
Grant/Contract Number:
AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 116; Journal Issue: 17; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; magnetite; IBAD; thin film; FORC; exchange bias; Environmental Molecular Sciences Laboratory
OSTI Identifier:
1166845
Alternate Identifier(s):
OSTI ID: 1420483

Kaur, Maninder, Jiang, Weilin, Qiang, You, Burks, Edward C., Liu, Kai, Namavar, Fereydoon, and McCloy, John S.. Exchange bias in polycrystalline magnetite films made by ion-beam assisted deposition. United States: N. p., Web. doi:10.1063/1.4900747.
Kaur, Maninder, Jiang, Weilin, Qiang, You, Burks, Edward C., Liu, Kai, Namavar, Fereydoon, & McCloy, John S.. Exchange bias in polycrystalline magnetite films made by ion-beam assisted deposition. United States. doi:10.1063/1.4900747.
Kaur, Maninder, Jiang, Weilin, Qiang, You, Burks, Edward C., Liu, Kai, Namavar, Fereydoon, and McCloy, John S.. 2014. "Exchange bias in polycrystalline magnetite films made by ion-beam assisted deposition". United States. doi:10.1063/1.4900747. https://www.osti.gov/servlets/purl/1166845.
@article{osti_1166845,
title = {Exchange bias in polycrystalline magnetite films made by ion-beam assisted deposition},
author = {Kaur, Maninder and Jiang, Weilin and Qiang, You and Burks, Edward C. and Liu, Kai and Namavar, Fereydoon and McCloy, John S.},
abstractNote = {Iron oxide films were deposited onto Si substrates using ion-beam-assisted deposition. The films were ~300 nm thick polycrystalline magnetite with an average crystallite size of ~6 nm. Additionally, 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. However, Raman spectroscopy and x-ray diffraction both indicate that the films are single-phase magnetite. Since no direct evidence of a second phase could be found, exchange bias likely arises due to defects at grain boundaries, possibly amorphous, creating frustrated spins. Since these samples have such small grains, a large fraction of the material consists of grain boundaries, where spins are highly disordered and reverse independently with external field. Furthermore, the high energy deposition process results in an oxygen-rich, argon-containing magnetite film with low temperature exchange bias due to defects at the high concentration of grain boundaries.},
doi = {10.1063/1.4900747},
journal = {Journal of Applied Physics},
number = 17,
volume = 116,
place = {United States},
year = {2014},
month = {11}
}