Alternating current magnetic susceptibility measurements in La1-xSrxCoO3 (x<=0.30) below 300 K

A dynamical magnetic susceptibility study on La1-xSrxCoO3 samples obtained by a coprecipitation method is reported for x less than or equal to 0.30. For x < 0.20 differences between zero field cooled and field cooled de magnetic susceptibility appear at a temperature T-a below the Curie point, T-C approximate to 240 K, as well as a magnetic freezing point at a temperature T-b < T-a. Alternating current magnetic susceptibility shows two maxima at these temperatures, which is interpreted as the evidence of different interaction processes between ferromagnetic clusters mediated by a matrix of changing spin-state Co3+ ions. For x greater than or equal to 0.20 an unique blocking process seems to take place due to the percolation of the ferromagnetic clusters, making unimportant the contribution of the matrix. (C) 1997 American Institute of Physics.