G. Souca, R. Dudric, Karsten Küpper, C. Tiușan, R. Tetean
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引用次数: 0
摘要
报告了 M = Fe、Mn、Cu 和 Al 的 GdCo1.8M0.2 的磁性能、能带结构结果和磁致效应。带状结构计算表明,所有样品都具有铁磁有序基态,与磁性测量结果完全一致。计算得出的磁矩和随合金成分的变化受到杂化机制的强烈影响,这一点通过对轨道投影局部态密度的分析得到了证实。XPS 测量显示,所研究的钴核级结合能并没有随着掺杂元素的变化而发生显著变化。Co 3s 核级光谱为我们提供了 Co 位点局部磁矩的直接证据,发现平均磁矩为 1.3 µB /原子,与理论估算和磁性测量结果十分吻合。从锰 3s 核级光谱中得到的磁矩值为 2.1 µB/Mn。磁熵变化的对称形状、阿罗特图和朗道系数的温度依赖性都清楚地表明了二阶相变。相对冷却功率 RCP(S)、归一化相对冷却功率 RCP(∆S)/∆B 和温度平均熵变值表明,这些化合物有望应用于磁制冷设备。
Band Structure Calculations, Magnetic Properties and Magnetocaloric Effect of GdCo1.8M0.2 Compounds with M = Fe, Mn, Cu, Al
The magnetic properties, band structure results, and magnetocaloric effect of GdCo1.8M0.2 with M = Fe, Mn, Cu, and Al are reported. The band structure calculations demonstrate that all the samples have a ferrimagnetically ordered ground state, in perfect agreement with the magnetic measurements. Calculated magnetic moments and variation with the alloy composition are strongly influenced by hybridisation mechanisms as sustained by an analysis of the orbital projected local density of states. The XPS measurements reveal no significant shift in the binding energy of the investigated Co core levels with a change in the dopant element. The Co 3s core-level spectra gave us direct evidence of the local magnetic moments on Co sites and an average magnetic moment of 1.3 µB /atom was found, being in good agreement with the theoretical estimation and magnetic measurements. From the Mn 3s core-level spectra, a value of 2.1 µB/Mn was obtained. The symmetric shapes of magnetic entropy changes, the Arrott plots, and the temperature dependence of Landau coefficients clearly indicate a second-order phase transition. The relative cooling power, RCP(S), normalized relative cooling power, RCP(∆S)/∆B, and temperature-averaged entropy change values indicate that these compounds could be promising candidates for applications in magnetic refrigeration devices.
期刊介绍:
Magnetochemistry (ISSN 2312-7481) is a unique international, scientific open access journal on molecular magnetism, the relationship between chemical structure and magnetism and magnetic materials. Magnetochemistry publishes research articles, short communications and reviews. Our aim is to encourage scientists to publish their experimental and theoretical results in as much detail as possible. Therefore, there is no restriction on the length of the papers. The full experimental details must be provided so that the results can be reproduced.