Magnetically disordered phase in epitaxial iron-deficient F e3 O4 thin films

J. A. Moyer, S. Lee, P. Schiffer, L. W. Martin

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

We report on the transport and magnetic properties of iron-deficient Fe3O4(Fe3-δO4) thin films grown with pulsed-laser deposition, where the stoichiometry and amount of cation vacancies are precisely controlled through changes in the oxygen partial pressure during growth. As the stoichiometry evolves from Fe3O4 to γ-Fe2O3, three distinct structural and magnetic regimes emerge: a Fe3O4-like regime, a γ-Fe2O3-like regime, and a transition regime. While reflection high-energy electron diffraction measurements reveal that films in all three regimes grow epitaxially cube-on-cube on MgO substrates, the transition-regime films are characterized by an absence of long-range, out-of-plane ordering in the film. Selected area electron diffraction measurements reveal the transition-regime films are well ordered on a local level, but not throughout the entire film. The structural disorder of the transition-regime films does not manifest itself in the transport properties, where a systematic change in resistivity, due primarily to variations in the Fe2+:Fe3+ cation ratio, occurs continuously throughout all three regimes. Large differences are observed, however, in the magnetic properties of the transition-regime films, which are reminiscent of magnetically disordered systems. We attribute this unique magnetically disordered state to magnetic frustration arising at the boundaries between the different locally ordered regions.

Original languageEnglish (US)
Article number064413
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume91
Issue number6
DOIs
StatePublished - Feb 13 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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