Unconventional critical magnetic behavior in the Griffiths ferromagnet La₀.₄Ca₀.₆MnO₂.₈□₀.₂ oxide
- Laboratoire de Physique Appliquée, Faculté des Sciences de Sfax, Université de Sfax B.P. 1171, 3000 SFAX (Tunisia)
- Institut Néel, CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble (France)
The effects of oxygen vacancy on the critical magnetic behavior in La₀.₄Ca₀.₆MnO₂.₈□₀.₂ around the paramagnetic-ferromagnetic (PM-FM) phase transition were investigated through various techniques such as modified Arrott plot, Kouvel-Fisher method and critical isotherm analysis via dc magnetization measurements recorded around the Curie temperature TC. The obtained critical exponents values are β~0.8, γ~0.7 and δ~1.882 with TC~164.5 K. Thus the scaling law γ+β=δβ is fulfilled. The critical exponents obey the single scaling-equation of state M(H,ε)|ε|{sup -β}=f{sub ±}(H|ε|{sup -(β+γ)}) where, f₊ for T>TC and f⁻ for T>TC. The found exponents are inconsistent with any known universality class. These results attributed to the existence of Griffiths Phase (Triki et al. (2012) [1]) seem to actually reflect the unconventional critical scaling of the magnetic susceptibility. - Graphical abstract: Modified Arrott plots: M{sup 1/β} vs. (μ₀H){sup 1/γ} with (a) mean-field model (β=0.5, γ=1), (b) 3D-Heisenberg model (β=0.365, γ=1.336), (c) 3D-Ising model (β=0.325, γ=1.24), (d) tricritical mean-field model (β=0.25, γ=1) and (e) (β=0.79, γ=0.71). Highlights: • Study of the critical behavior for La₀.₄Ca₀.₆MnO₂.₈□₀.₂ compound. • A typical second-order magnetic transition near TC. • Unconventional critical exponents were found.
- OSTI ID:
- 22306267
- Journal Information:
- Journal of Solid State Chemistry, Vol. 201; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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