Ferromagnetic resonance and intrinsic properties of La0.67Ba0.33MnOz

Systematic magnetization and ferromagnetic resonance (FMR) measurements have been performed on thin-him samples of La0.67Ba0.33MnOz (T-C similar to 340 K). It is found from the FMR data that as-grown films showbread lines whose width Gamma increases to nearly 1 kOe as T reduced to 77 K. The increase roughly follows the increase in the magnetization suggesting magnetic inhomogeneity as the main cause for the rise in Gamma. However when films were properly annealed in O-2, we obtained narrow lines (Gamma similar to 200 Oe at 10 GHz). Gamma was effectively independent of temperature and linearly dependent upon microwave frequency, both of which are strong signs that, we have succeeded in obtaining a uniform, homogeneous manganite sample. Having gotten a uniform material, we have measured the intrinsic properties of this system. (C) 1996 American Institute of Physics.