Abstract
In the present work we report the structural, electron spin resonance (ESR) and magnetic properties of La0.37D0.30Ca0.33MnO3 (D = Bi, Sm) manganites synthesized by sol-gel method. The critical behavior at the critical point, where the system undergoes phase transition from paramagnetic (PM) to ferromagnetic (FM) state, is investigated by using modified-Arrott plots, Kouvel-Fisher method and critical isotherm analysis. Both the samples show second-order phase transition near the critical point. The decrease in magnetization (M), Curie temperature (TC), evolution of spin or cluster glass behavior and the nature of second-order phase transition compared to the first-order transition reported in the literature for La0.67Ca0.33MnO3 are ascribed to disorder caused by the size mismatch of the A-site cations with Bi and Sm doping at La-site.
Highlights
Manganese oxides with ABO3 perovskite structure have been extensively studied since the discovery of colossal magnetoresistance (CMR).[1,2,3] The significant changes in structure, magnetic and magnetoresistive (MR) properties of manganites can be achieved by varying particle size,[4,5] A/B-site doping[6,7,8,9] and oxygen stoichiometry.[10]
The decrease in magnetization (M), Curie temperature (TC), evolution of spin or cluster glass behavior and the nature of second-order phase transition compared to the first-order transition reported in the literature for La0.67Ca0.33MnO3 are ascribed to disorder caused by the size mismatch of the A-site cations with Bi and Sm doping at La-site
The present results suggest that it is not the A-site ionic radius alone which decides the nature of FM-PM transition
Summary
Manganese oxides with ABO3 perovskite structure have been extensively studied since the discovery of colossal magnetoresistance (CMR).[1,2,3] The significant changes in structure, magnetic and magnetoresistive (MR) properties of manganites can be achieved by varying particle size,[4,5] A/B-site doping[6,7,8,9] and oxygen stoichiometry.[10]. Anwar et al.[13] studied the disorder effects on structure, magnetic and magnetocaloric properties in La0.7−xSmxCa0.3MnO3 (0 ≤ x ≤ 0.3)manganites. The studies on these compounds confirm the first order FM transition in undoped sample and second order FM transition in doped sample. The decrease in the value of TC is observed with Sm doping They have suggested that these compounds can be used as potential magnetic refrigerating material with a wide range of temperature. In La0.37Bi0.30Ca0.33MnO3 and La0.37Sm0.30Ca0.33MnO3 compounds, the ratio of La, Bi(Sm) and Ca ions at A-site is approximately same This is likely to help in understanding the effect of different doping elements in same quantity on the properties of LCMO system
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