Spin waves and transport properties in ferromagnetic Co-Al-O and Fe-Al-O granular films: A Brillouin scattering study

Akira Yoshihara, Shigehiro Ohnuma, Hiroyasu Fujimori, Shintaro Nakamura, Tsutomu Nojima

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

A systematic Brillouin light scattering (BLS) study on long-wavelength spin waves (SWs) in ferromagnetic TM-Al-O (TM = Co, Fe) nano-granular films with thickness of >1 μm was performed under magnetic fields of up to 4 kOe at room temperature. BLS spectra consist of a pair of bulk SW peaks on both frequency sides and a surface localized SW peak only on the positive frequency side in this study. These SW frequencies as a function of the magnetic field can be fully reproduced by the magnetostatic frequency formula developed for a semi-infinite uniform ferromagnetic medium with an exchange coupling and an in-plane uniaxial magnetic anisotropy. We determined a set of the magnetic constants including the exchange field HE for each film. Combining the exchange field HE with the electrical resistivity ρ for each film at room temperature, we found an inverse-square law given by ρ = a(HE)-2 for both the Co and Fe granular films with a Fe = 30:3 μΩ·cm·(kOe)2 and a Co = 22:1 μΩ·cm·(kOe)2, respectively.

Original languageEnglish
Article number094704
Journaljournal of the physical society of japan
Volume77
Issue number9
DOIs
Publication statusPublished - 2008 Sep

Keywords

  • Brillouin scattering
  • Exchange coupling
  • Nanogranular film
  • Resistivity
  • Spin wave

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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