Critical Exponents at Curie Transition in Nd(Co<sub>0.8</sub>Fe<sub>0.2</sub>)<sub>2</sub> Compound

本文通过直流磁化测量研究了Nd(Co0.8Fe0.2)2在居里温度(TC)附近的临界行为。利用Kouvel-Fisher法、改进的Arrotts图法以及临界等温分析，获得了临界指数 β=0.38( 5 ) 、 γ=1.31( 4 ) 和 δ=4.41( 3 ) 。通过 M | t | −β 与 H | t | −( β+γ ) 的对数标度图验证了所得临界指数的可靠性。此外，临界指数 β 、 γ 、 δ 以及交换相互作用 J( r )~1/ r 4.87 表明，Nd(Co0.8Fe0.2)2符合三维海森堡模型，其中短程相互作用占主导地位。The critical behavior around the Curie temperature (TC) of Nd(Co0.8Fe0.2)2 was investigated by dc magnetization measurement. The critical exponents β=0.38( 5 ) , γ=1.31( 4 ) and δ=4.41( 3 ) were carried out by Kouvel-Fisher, modified Arrotts Plot methods, as well as critical isothermal analysis. The reliability of the obtained critical exponents was verified by the logarithmic scaling plot of M | t | −β versus H | t | −( β+γ ) . Besides, the exponents β, γ, and δ, as well as the exchange interaction J( r )~1/ r 4.87 proposed a three-dimensional Heisenberg model for Nd(Co0.8Fe0.2)2 in which the short-range interaction becomes dominant.