Magnetic properties of La_{1 <i>x</i>}Sr_<i>x</i>CoO₃(<i>x</i>= 0.15 and 0.3)

Abstract

Neutron diffraction, transversal field μSR and magnetization studies of La_1-<em>x</em>Sr_<em>x</em>CoO₃ with <em>x</em> = 0.15 and 0.3 has been performed. Long-range ferromagnetic ordering has been found only in the <em>x</em> = 0.3 sample. Magnetization measurements indicate the inhomogeneous magnetic state of this system. Magnetization data confirm well defined long-range ordering for the <em>x</em> = 0.3 sample with <em>T</em>_C ≈ 220 K, whereas for the <em>x</em> = 0.15 compound this temperature marks the onset of magnetic order within ferromagnetic clusters. μSR data confirm that the transition in the ferromagnetic phase takes place in the large fraction of the <em>x</em> = 0.3 sample, but not in all of the volume. This data also provide evidence for the absence of long-range magnetic ordering for the <em>x</em> = 0.15 sample and show that even short-range ordering takes place only in part of the sample volume. Thus, all these data are in agreement with the phase separation scenario of the concentration phase transition in cobaltites.