Abstract We report the magnetic properties and critical behavior of La 0.7 Sr 0.3 Mn 1- x Cu x O 3 ( x = 0.02 and 0.04) perovskite manganites. Results of temperature-dependent magnetization show that the Curie temperature decreases from 360 K ( x = 0.02) to 356 K ( x = 0.03) with increasing Cu content. Field dependence of isothermal entropy change data is used to estimate the critical exponents, and the results satisfied the requirements of the scaling law. Calculated critical exponents are β = 0.4641, γ = 1.1623, and δ = 3.546 for x = 0.02, and β = 0.4486, γ = 1.2024, and δ = 3.6805 for x = 0.04. These results indicate that La 0.7 Sr 0.3 Mn 1- x Cu x O 3 can be characterized by long-range mean-field behavior. Thus, the field dependence of magnetic entropy change can be effectively used in studying the critical behavior of magnetic materials.

中文翻译：

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使用 La 0.7 Sr 0.3 Mn 1-x Cu x O 3 ( x =0.02 和 0.04) 中磁熵变化的场相关性研究临界行为

摘要 我们报告了 La 0.7 Sr 0.3 Mn 1- x Cu x O 3 (x = 0.02 和 0.04) 钙钛矿锰矿的磁性和临界行为。随温度变化的磁化强度结果表明，随着 Cu 含量的增加，居里温度从 360 K ( x = 0.02) 降低到 356 K ( x = 0.03)。利用等温熵变数据的场相关性来估计临界指数，结果满足标度律的要求。计算出的临界指数为 β = 0.4641、γ = 1.1623 和 δ = 3.546（x = 0.02），β = 0.4486、γ = 1.2024 和 δ = 3.6805（x = 0.04）。这些结果表明，La 0.7 Sr 0.3 Mn 1- x Cu x O 3 可以通过长程平均场行为来表征。因此，磁熵变的场相关性可以有效地用于研究磁性材料的临界行为。