Coexistence of ferromagnetic and glassy behavior in semiconducting LaNi0.2Co0.8O3

Systematic dc and ac magnetic susceptibility studies have been performed on single-phase LaNi0.2Co0.8O3 powder samples. Evidence of hysteresis loops supports the existence of ferromagnetic correlations that lead to a rapid increase of the dc susceptibility at Tless than or equal to55 K. The frequency dependence of the ac susceptibility is suggestive of a spin-glass-like phase. The temperature dependence of the nonlinear susceptibility components, chi(2) and chi(3), in zero dc magnetic field demonstrates the existence of spontaneous magnetization, appears to exclude the occurrence of a canonical spin-glass phase and instead indicates that a cluster-glass phase occurs in LaNi0.2Co0.8O3. It is suggested that the spontaneous magnetization in this system is due to the existence of Ni-based clusters with strong intracluster ferromagnetic correlations, embedded randomly in a paramagnetic matrix. (C) 2002 American Institute of Physics.