Unusual perpendicular anisotropy in Co2TiSi films

Yunlong Jin, Shah Valloppilly, Parashu Kharel, Rohit Pathak, Arti Kashyap, Ralph Skomski, D. J. Sellmyer

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Thin films of Co2TiSi on MgO are investigated experimentally and theoretically. The films were produced by magnetron sputtering on MgO(0 0 1) and have a thickness of about 100 nm. As bulk Co2TiSi, they crystallize in the normal cubic Heusler (L21) structure, but the films are slightly distorted (c/a = 1.0014) and contain some antisite disorder. The films exhibit a robust perpendicular anisotropy of 0.5 MJ m-3. This result is surprising for several reasons. First, surface and interface anisotropies are too small to explain perpendicular anisotropy in such rather thick films. Second, Co2TiSi has a substantial magnetization and crystallizes in a cubic Heusler structure, so that conventional wisdom predicts a preferential magnetization direction in the film plane rather than perpendicular. Third, the lattice strain of 0.14% is unable to account for the perpendicular anisotropy. We explain the perpendicular anisotropy as a quasicubic symmetry breaking chemical-ordering effect promoted by the substrate.

Original languageEnglish (US)
Article number035001
JournalJournal of Physics D: Applied Physics
Volume52
Issue number3
DOIs
StatePublished - Jan 16 2019

Keywords

  • Heusler alloy
  • epitaxial thin films
  • perpendicular magnetic anisotropy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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