Critical exponents of the ferromagnetic-paramagnetic phase transition ofLa1−xSrxCoO3(0.20<~x<~0.30)

The critical exponents of the second-order ferromagnetic-paramagnetic phase transition of (Formula presented) (Formula presented) compounds are obtained. The results (Formula presented) (Formula presented) and (Formula presented) are qualitatively different than those reported in the literature for parent manganites, and are taken as the indication of the absence of long-range interactions below the Curie point. Electronic phase segregation in hole-rich ferromagnetic and hole-poor (Formula presented)-like regions is supposed to explain the observations. The hole-poor regions would dilute the magnetic lattice and prevent the occurrence of long-range order. Also, a spin transition of the (Formula presented) ions at (Formula presented) or the hole-poor regions (acting equivalently to missed spin clusters in amorphous ferromagnets) could be the reason for the high β value in the framework of a Heisenberg model. &#169; 1999 The American Physical Society.