Glassy ferromagnetism in La^sub 0.75^Sr^sub 0.25-x^K^sub x^CoO3 polycrystalline perovskite cobaltites

• Published in: Journal of electroceramics 2014-05, Vol.32 (2-3), p.224
• Main Authors: Mahfoudh, N, Koubaa, M, Cheikhrouhou-koubaa, W, Cheikhrouhou, A
• Format: Article
• Language: English
• ISSN: 1385-3449; 1573-8663
• DOI: 10.1007/s10832-013-9877-x

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) In this paper, the structural and magnetic properties of La^sub 0.75^Sr^sub 0.25-x^K^sub x^CoO3 (0≤x≤0.15) powder samples are reported. X-ray diffraction analysis using Rietveld refinement show that all our samples crystallize in the rhombohedral structure with ... space group. At low temperatures, with increasing K amount, the samples change from ferromagnetic like behavior (x=0, 0.05 and 0.1) to spin glass one (x=0.15). The ferromagnetic-paramagnetic transition temperature decreases with increasing K amount from 235K (x=0) to 200K (x=0.1). In the paramagnetic phase, all our synthesized samples obey the Curie-Weiss law. In the vicinity of T^sub C^, the magnetic entropy change |ΔS ^sub M^| for La^sub 0.75^Sr^sub 0.2^K^sub 0.05^CoO3 sample reached maximum values of 0.47Jkg/K and 2.27Jkg/K under magnetic field variation in the range 1T and 7T, respectively. The magnetization hysteresis loops demonstrate a weakening the ferromagnetism with increasing K content.[PUBLICATION ABSTRACT]