Critical behavior in Ga-doped manganites La_0.75(Sr,Ca)_0.25Mn_{1?an style='font-style: italic'>x}Ga_xO₃ (0¡Üan style='font-style: italic'>x¡Ü0.1)

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• 作者：A. Omri ; A. Tozri ; M. Bejar ; E. Dhahri ; E.K. Hlil
• 关键词：Perovskite manganite ; Critical behavior ; Critical exponent
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：2012
• 出版时间：September, 2012
• 年：2012
• 卷：324
• 期：19
• 页码：3122-3128
• 全文大小：960 K

文摘

The critical properties of perovskite manganite AMn_1?xGa_xO₃ (A=La_0.75Ca_0.08Sr_0.17, x=0, 0.05 and 0.1) at the ferromagnetic-paramagnetic transition have been analyzed. Experimental results revealed that all samples exhibit a second-order magnetic phase transition. The estimated critical exponents derived from the magnetic data using various techniques such as modified Arrott plot, Kouvel-Fisher method, and critical magnetization isotherms M(T_C, H). The critical exponent values for the undoped compound were found to match well with those predicted for the three-dimensional Heisenberg model (¦Â=355¡À0.007, ¦Ã=1.326¡À0.002, ¦Ä=4.90¡À0.01). While on non-magnetic Ga substitution it tends towards mean-field with long-range interaction. The mean-field model might be due to the random dilution of the Mn sublattice by non-magnetic ion Ga³⁺ and/or the development of the physical size of the clusters which enhance the dipole-dipole interaction.