The magnetic properties of GdN thin films with bulk and 2.4% extended lattice parameters have been studied by x-band ferromagnetic resonance (FMR) spectroscopy. Simple, anisotropic, single line FMR spectra are observed in the $0\text{to}18\mathrm{kOe}$ field range. Both films show an in-plane easy axis of magnetization due to the predominance of the shape related demagnetization fields. The films deposited on (100) Si substrates are strained with uniaxial anisotropy constants up to $K_u=+5\times {10}^6\mathrm{erg}∕{\mathrm{cm}}^3$ at $T=4\mathrm{K}$. The lattice extension reduces the magnetization and decreases the Curie temperature from $69\mathrm{K}$ for the bulk films to $20\mathrm{K}$ for the films with extended lattice constants. Highly increased FMR linewidths are observed for the lattice extended films indicating large, local variations of the demagnetization fields.

• Received 22 May 2006

DOI:https://doi.org/10.1103/PhysRevB.74.245330