Epitaxial growth and properties of MBE-grown ferromagnetic Co-doped TiO2 anatase films on SrTiO3(001) and LaAlO3(001)

S. A. Chambers, C. M. Wang, S. Thevuthasan, T. Droubay, D. E. McCready, A. S. Lea, V. Shutthanandan, Jr F. Windisch

Research output: Contribution to journalArticle

128 Citations (Scopus)

Abstract

We have investigated the heteroepitaxial growth and materials properties of pure and Co-doped TiO2 anatase on SrTiO3(001) and LaAlO3(001), grown by oxygen plasma assisted molecular beam epitaxy. This material is a promising new diluted magnetic semiconductor that shows large magnetization and a Curie temperature well above room temperature. We have found that epitaxial films with the highest crystalline quality and most uniform distribution of Co result when a rather slow growth rate (∼0.01 nm/s) is used over a substrate temperature range of 550-600 °C on LaAlO3(001). These conditions result in layer-by-layer growth of single-crystal films and a very low density of extremely small nanocrystalline inclusions. In contrast, growth at a higher rate (∼0.04 nm/s) leads to extensive formation of secondary-phase rutile nanocrystals to which Co diffuses and segregates. The rutile nanocrystals nucleate on the evolving anatase film surface in such a way that lattice strain between the two phases is minimized. Cobalt appears to substitute for Ti in the lattice and exhibits a +2 formal oxidation state. Both pure and Co-doped films can be grown as n-type semiconductors by controlled incorporation of oxygen atom vacancies. Free electrons are required to couple the Co(II) spin to a ferromagnetic state.

Original languageEnglish
Pages (from-to)197-210
Number of pages14
JournalThin Solid Films
Volume418
Issue number2
DOIs
Publication statusPublished - 15 Oct 2002
Externally publishedYes

Fingerprint

Epitaxial growth
Molecular beam epitaxy
anatase
Titanium dioxide
Nanocrystals
rutile
nanocrystals
Oxygen
Epitaxial films
Curie temperature
n-type semiconductors
Vacancies
Cobalt
Magnetization
Materials properties
oxygen plasma
Single crystals
Semiconductor materials
free electrons
Crystalline materials

Keywords

  • Magnetic properties and measurements
  • Molecular beam epitaxy (MBE)
  • Semiconductors
  • Titanium oxide

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Condensed Matter Physics
  • Surfaces and Interfaces

Cite this

Chambers, S. A., Wang, C. M., Thevuthasan, S., Droubay, T., McCready, D. E., Lea, A. S., ... Windisch, J. F. (2002). Epitaxial growth and properties of MBE-grown ferromagnetic Co-doped TiO2 anatase films on SrTiO3(001) and LaAlO3(001). Thin Solid Films, 418(2), 197-210. https://doi.org/10.1016/S0040-6090(02)00709-5

Epitaxial growth and properties of MBE-grown ferromagnetic Co-doped TiO2 anatase films on SrTiO3(001) and LaAlO3(001). / Chambers, S. A.; Wang, C. M.; Thevuthasan, S.; Droubay, T.; McCready, D. E.; Lea, A. S.; Shutthanandan, V.; Windisch, Jr F.

In: Thin Solid Films, Vol. 418, No. 2, 15.10.2002, p. 197-210.

Research output: Contribution to journalArticle

Chambers, SA, Wang, CM, Thevuthasan, S, Droubay, T, McCready, DE, Lea, AS, Shutthanandan, V & Windisch, JF 2002, 'Epitaxial growth and properties of MBE-grown ferromagnetic Co-doped TiO2 anatase films on SrTiO3(001) and LaAlO3(001)', Thin Solid Films, vol. 418, no. 2, pp. 197-210. https://doi.org/10.1016/S0040-6090(02)00709-5
Chambers, S. A. ; Wang, C. M. ; Thevuthasan, S. ; Droubay, T. ; McCready, D. E. ; Lea, A. S. ; Shutthanandan, V. ; Windisch, Jr F. / Epitaxial growth and properties of MBE-grown ferromagnetic Co-doped TiO2 anatase films on SrTiO3(001) and LaAlO3(001). In: Thin Solid Films. 2002 ; Vol. 418, No. 2. pp. 197-210.
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AU - Thevuthasan, S.

AU - Droubay, T.

AU - McCready, D. E.

AU - Lea, A. S.

AU - Shutthanandan, V.

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