磁矩
磁化
居里温度
化学
凝聚态物理
铁磁性
交换互动
分析化学(期刊)
材料科学
磁场
物理
色谱法
量子力学
作者
Xubo Liu,Ikenna C. Nlebedim
出处
期刊:Crystals
[Multidisciplinary Digital Publishing Institute]
日期:2024-04-16
卷期号:14 (4): 370-370
标识
DOI:10.3390/cryst14040370
摘要
Partial replacement of Fe by Co is an effective method to increase Curie temperature (TC), which improves the thermal stability of magnetic properties in Nd2Fe14B-based permanent magnets. The correlation between Fe substitution and magnetic properties has been studied in Nd2(Fe,Co)14B via a first-principles calculation. The calculated Fe substitution energies indicate that the Co atoms avoid the 8j2 site, which agrees with the experiments. The Co atoms are ferromagnetically coupled with Fe sublattice and show magnetic moments of about 1.2 to 1.7 μB at different crystallographic sites, less than that of Fe (2.1–2.7 μB), resulting in the decrease in total magnetization at ground state (0 K) with increasing Co content. The effective exchange interaction parameter, derived from the energy difference between varied magnetic structures, increases from 7.8 meV to 17.0 meV with increasing Co content from x = 0 to x = 14 in Nd2Fe14−xCoxB. This change in the effective exchange interaction parameter is responsible for the enhancement of TC in Nd2(Fe,Co)14B. The total magnetization at 300 K, derived from mean-field theory, shows a peak maximum value at x = 1 in Nd2Fe14−xCoxB. The phenomenon results from the interplay between the reduction of the magnetic moment in the Fe(Co) sublattice and the enhancement of TC with increasing Co content.
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