Brillouin light scattering from spin waves in epitaxial hcp Co films

Abstract

Listen

Translate article

The first and second magnetic anisotropy constants ${K}_{1}$ and ${K}_{2}$ and the spin wave (SW) stiffness constant ${D}_{\mathrm{BLS}}$ of epitaxial $(101\ifmmode\bar\else\textasciimacron\fi{}0)$ Co films of $450\ifmmode\pm\else\textpm\fi{}10\mathrm{\AA{}}$ in thickness have been determined by Brillouin light scattering (BLS) at room temperature in magnetic fields of up to 5.0 kOe. We employed three scattering geometries: (A) magnetic fields applied along the in-plane easy direction, (B) magnetic fields applied along the in-plane hard direction, and (C) a constant magnetic field rotated from the in-plane easy direction to the in-plane hard direction. We always examined SW's propagating perpendicular to the magnetic field. Numerical analyses of the SW frequencies by a continuum dipole-exchange model with the magnetic anisotropy allowed us to obtain values of ${D}_{\mathrm{BLS}}=(3.46\ifmmode\pm\else\textpm\fi{}0.35)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\mathrm{Oe}{\mathrm{cm}}^{2},$ ${K}_{1}=(3.45\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\times\else\texttimes\fi{}{10}^{6}{\mathrm{e}\mathrm{r}\mathrm{g}/\mathrm{c}\mathrm{m}}^{3}$ and ${K}_{2}=(0.90\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\times\else\texttimes\fi{}{10}^{6}{\mathrm{e}\mathrm{r}\mathrm{g}/\mathrm{c}\mathrm{m}}^{3}.$ These values are in good agreement with the BLS values reported for the $(101\ifmmode\bar\else\textasciimacron\fi{}0)$ epitaxial Co films by M. Grimsditch et al. [Phys. Rev. B 56, 2617 (1997)]. We also measured temperature development of film magnetization using a superconducting quantum inerference device magnetometer in a temperature range between 4.2 and 100 K. The temperature development of magnetization obeys the ${T}^{3/2}$ law and can be well reproduced by SW theory with BLS values of the magnetic constants.