Evolution of magnetic state of ultrathin Co films with Volmer-Weber growth

Yu Shiratsuch, Tatsuya Murakami, Yasushi Endo, Masahiko Yamamoto

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The surface structure and magnetic state of ultrathin Co films with Volmer-Weber growth (V-W growth) on α-Al2O3(0001) have been investigated as a function of Co thickness. Due to V-W growth, Co forms particles with a diameter of approximately 5 nm. Originating from the particle structure, the magnetic state of Co is superparamagnetism below a thickness of 1.1 nm, and evolves to ferromagnetism as the Co thickness increases. The transition occurs for a wide thickness range, i.e., 1 to 3 nm. Due to the wide-range transition, it enables to observe the coexistence of superparamagnetism and ferromagnetism at a thickness of around 2 nm. The wide range transition of the magnetic state is explained by the slow coalescence of Co particles. The structural transition would be dominated by the large interface energy between Co and α-Al2O2(0001).

Original languageEnglish
Pages (from-to)8456-8461
Number of pages6
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume44
Issue number12
DOIs
Publication statusPublished - 2005 Dec 8
Externally publishedYes

Keywords

  • Superparamagnetism
  • Ultrathin Co film
  • Volmer-Weber growth

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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