Brillouin scattering from spin waves in sputtered Co-Zr films

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Abstract
Thermally excited spin waves in thin Co91‐Zr9 sputtered films have been studied at room temperature by Brillouin scattering in external magnetic fields of up to 3.5 kOe. In order to precisely determine the g factor and the surface exchange constant, we extensively studied the Damon–Eshbach mode in a 1‐μm‐thick film. From the slope of the surface magnon frequency in an external magnetic field, the g factor of 2.17±0.04 is determined. The surface exchange stiffness constant Ds has been determined by examining the surface wave‐vector dependence on the surface magnon frequency. We obtained a value of Ds =6.9±2.0×10−9 Oe cm2. The best way to determine the bulk stiffness constant is to observe the standing spin waves excited in a thin film whose thickness is less than 200 nm. We could observe scattering from the standing spin waves of up to a third order in a film of 85±5 nm thick. The bulk exchange stiffness constant Db of 2.2±0.4×10−9 Oe cm2 is obtained from the external field dependence of the standing spin‐wave frequencies.