Brillouin study of long-wavelength spin waves in quasimonatomic Co films with uniaxial perpendicular magnetic anisotropy

Akihiro Murayama, Kyoko Hyomi, James Eickmann, Charles M Falco

Research output: Contribution to journalArticle

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Abstract

We have observed spin-wave Brillouin light scattering from ultrathin Co/Au/Cu(111) films with Co thicknesses tCo down to 1 monolayer (ML) and with a 1-ML Au interlayer. The detection of a well-defined spin-wave spectrum and the field dependence of its frequency show directly long-range collective and ferromagnetic ordering in these films at room temperature. From the field dependence of the spin-wave frequency, we derive uniaxial perpendicular magnetic anisotropy constants as a function of tCo with various overlayer materials, including Cu, Pd, and Au. With a Cu overlayer, we observe that the first-order perpendicular anisotropy Ku(1) obeys well a linear relation between Ku(1)tCo and tCo for tCo≧1.5 ML, which indicates a constant contribution of the interface anisotropy of 0.16 mJ/m2 in addition to the volume anisotropy of 0.73 MJ/m3. With an Au or a Pd overlayer, we find that both the interface and volume anisotropies are significantly larger than those with the Cu overlayer. We quantify magnetic inhomogeneities from the field dependence of the spectrum width. With the Au or Pd overlayer, Ku(1) shows a steep decrease with decreasing tCo for tCo <3.0 ML, which agrees well with a significant increase in the structure-related magnetic inhomogeneity. We show directly that long-ranged ferromagnetic ordering exists, with the perpendicular anisotropy, in our quasimonatomic Co films thinner than 1.5 ML. Ku(1) for each overlayer tends to be zero at 1 ML of Co, accompanied by heavy damping of the spin wave. In addition, we find the second-order perpendicular anisotropy is still maintained with a comparable value to Ku(1) in such quasimonatomic Co films, indicating significant deformation of the uniaxial anisotropy.

Original languageEnglish (US)
Pages (from-to)8984-8992
Number of pages9
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume61
Issue number13
StatePublished - Apr 1 2000

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Spin waves
Magnetic anisotropy
magnons
Anisotropy
Monolayers
Wavelength
anisotropy
wavelengths
inhomogeneity
Brillouin scattering
Light scattering
Damping
interlayers
light scattering
damping
Thin films
room temperature
thin films

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Brillouin study of long-wavelength spin waves in quasimonatomic Co films with uniaxial perpendicular magnetic anisotropy. / Murayama, Akihiro; Hyomi, Kyoko; Eickmann, James; Falco, Charles M.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 61, No. 13, 01.04.2000, p. 8984-8992.

Research output: Contribution to journalArticle

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