Magnetic and Moessbauer studies of some mixed cobaltites of the lanthanides and alkali metals

Magnetic and Moessbauer studies are carried out on compounds M/sub x/Ln/sub 1-x/CoO3 where M is Ba or Sr and Ln is La, Nd or Dy. All compositions with x > 0.2 with the exception of the dysprosium compounds are ferromagnetic at low temperatures. From hysteresis and initial susceptibility studies, it is concluded that they contain a number of single domain clusters in a paramagnetic matrix. Moessbauer spectra of Ba/sub 0.3/Nd/sub 0.7/CoO3 and Ba/sub 0.5/Dy/sub 0.5/CoO3 show two resonance lines and that of Sr/sub 0.5/La/sub 0.5/CoO3 shows a single line spectrum at all temperatures, and no hyperfine spectra are shown even far below T/sub C/. The results are interpreted in terms of short-range magnetic ordering in these systems. (author)