Magneto-resistance and superparamagnetism in magnetite films on MgO and MgAl2O4

W. Eerenstein*, L. Kalev, L. Niesen, T. T M Palstra, T. Hibma

*Corresponding author for this work

Research output: Contribution to journalConference articleAcademicpeer-review

40 Citations (Scopus)

Abstract

The present study is a comparison of the resistive and magnetic properties of ultrathin epitaxial Fe3O4 films grown on MgO(0 0 1) and MgAl2O4(0 0 1). Such films on MgO are known to contain anti-phase boundaries, which cause magneto-resistance in these films, an increased resistivity with respect to the bulk and superparamagnetic behaviour for films below 5 nm thickness. Ultrathin films on MgAl2O4 show a very similar behaviour as the resistivity is also increased with respect to the bulk, but is still lower than the resistivity of films grown on MgO. This indicates a larger domain size in the films grown on MgAl2O4. This is supported by the observed magneto-resistance that is larger than for films grown on MgO. Mössbauer spectroscopy analysis of a 1.7nm thick film on MgO indicates that all magnetic moments in the film are fluctuating, whereas for the film on MgAl2O4 a sextet with a parabolic background is observed. This shows that some domains are small enough for the moment to fluctuate while in larger ones, the moments are fixed; this also indicates that the domains in the film on MgAl2O4 are larger than in the film grown on MgO.

Original languageEnglish
Pages (from-to)73-76
Number of pages4
JournalJournal of magnetism and magnetic materials
Volume258-259
DOIs
Publication statusPublished - 1 Mar 2003
Externally publishedYes
EventSecond Moscow International Symposium on Magnetism 2001 - Moscow, Russian Federation
Duration: 20 Jun 200124 Jun 2001
Conference number: 2

Keywords

  • Magnetite
  • Magneto-resistance
  • Spin polarization
  • Spinel
  • Superparamagnetism

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