Critical Behavior Near the Paramagnetic-Ferromagnetic Phase Transition in La{sub 1−x}Sr{sub x}CoO{sub 3} (x = 0.3 and x = 0.5) Cobaltites

Journal Article · Thu Feb 15 04:00:00 EST 2018 · Journal of Superconductivity and Novel Magnetism

DOI:https://doi.org/10.1007/S10948-017-4225-Z· OSTI ID:22782491

Amor, A. Ben; Cheikhrouhou-Koubaa, W.; Cheikhrouhou, A. ^[1]

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1. Centre de Recherche en Numérique de Sfax, Laboratoire des Technologies des Systèmes Smart (LT2S) (Tunisia)

In this work, we present the study of structural, magnetic and critical behavior of La{sub 1−x}Sr{sub x}CoO{sub 3} (x = 0.3 and 0.5) cobaltites. X-ray diffraction analysis using the Rietveld refinement shows that the sample La{sub 0.7}Sr{sub 0.3}CoO{sub 3} crystallizes in a rhombohedral distorted perovskite structure with R3̄c space group, while La{sub 0.5}Sr{sub 0.5}CoO{sub 3} exhibits both phases rhombohedric and cubic, with R3̄c and Pm3̄m space groups. Our samples exhibit thermo-magnetic irreversibility behavior in the magnetization data under a magnetic applied field of 0.05 T. The temperature dependence of magnetic susceptibility at higher temperatures for La{sub 0.7}Sr{sub 0.3}CoO{sub 3} sample reveals the presence of the Griffiths’ phase above the Curie temperature, while it follows the Curie–Weiss law perfectly for La{sub 0.5}Sr{sub 0.5}CoO{sub 3}. Different techniques including the modified Arrott plot, the Kouvel-Fisher method and the critical isotherm analysis have been used to analyze the paramagnetic-ferromagnetic phase transition. The values of the critical exponents associated to this transition were close to those expected in the mean-field model. The validity of the calculated critical exponents has been confirmed by the scaling equation of state. The determined critical exponents using various methods are found to follow the scaling equation with the magnetization data scaled into two different curves below and above the critical temperature.

• OSTI ID: 22782491
• Journal Information: Journal of Superconductivity and Novel Magnetism, Journal Name: Journal of Superconductivity and Novel Magnetism Journal Issue: 2 Vol. 31; ISSN 1557-1939
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COBALT COMPOUNDS
CRITICAL TEMPERATURE
CUBIC LATTICES
CURIE POINT
EQUATIONS OF STATE
ISOTHERMS
LANTHANUM COMPOUNDS
MAGNETIC SUSCEPTIBILITY
MAGNETIZATION
MEAN-FIELD THEORY
OXYGEN COMPOUNDS
PARAMAGNETISM
PHASE TRANSFORMATIONS
SPACE GROUPS
STRONTIUM COMPOUNDS
TEMPERATURE DEPENDENCE
TRIGONAL LATTICES
X-RAY DIFFRACTION