Systematic magnetization, resistivity, and ferromagnetic resonance measurements have been done on bulk as well as thin-film samples of ${\mathrm{La}}_{\frac{2}{3}}{\mathrm{Ba}}_{\frac{1}{3}}\mathrm{Mn}{\mathrm{O}}_3$. Bulk specimens and as-grown films show broad lines whose width increases to nearly 1 kOe as $T$ is reduced to 77 K. At low $T$, the bulk magnetization is as expected for fully aligned spins [$4\pi M\left(0\right)=7.2\mathrm{}$ kOe]. As-grown films, however, show somewhat smaller values. The main finding is that films which have been annealed for several days at 1000 °C in an atmosphere of ${\mathrm{O}}_2$ exhibit narrow (∼200 Oe at 10 GHz) linewidths which are effectively independent of temperature. These are, to our knowledge, the narrowest lines observed in giant magnetoresistance materials, a strong indication of homogeneity. The low-$T$ magnetization is near the expected value, and its temperature dependence is highly suggestive of low-lying spin-wave excitations.

• Received 20 March 1995

DOI:https://doi.org/10.1103/PhysRevB.52.15058