Brillouin light scattering from spin waves in epitaxial hcp Co films

The first and second magnetic anisotropy constants $K_1$ and $K_2$ and the spin wave (SW) stiffness constant $D_{\mathrm{BLS}}$ of epitaxial $\left(101\mathrm{}¯0\right)$ Co films of $450\pm 10\mathrm{\AA }$ 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 $D_{\mathrm{BLS}}=(3.46\mathrm{}\pm 0.35)\times {10}^{-9}\mathrm{Oe}{\mathrm{cm}}^2,$ $K_1=(3.45\mathrm{}\pm 0.1)\times {10}^6{\mathrm{e}\mathrm{r}\mathrm{g}/\mathrm{c}\mathrm{m}}^3$ and $K_2=(0.90\mathrm{}\pm 0.1)\times {10}^6{\mathrm{e}\mathrm{r}\mathrm{g}/\mathrm{c}\mathrm{m}}^3.$ These values are in good agreement with the BLS values reported for the $\left(101\mathrm{}¯0\right)$ 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.