晶界畸变重新定向Nd2Fe14B中局域4f易轴并使轻、重镧系元素分裂
Grain Boundary Distortion Reorients the Local 4f Easy Axis and Splits Light from Heavy Lanthanides in Nd2Fe14B
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中文总结 AI 辅助
本研究通过嵌入多参考计算揭示Nd2Fe14B晶界畸变使轻、重镧系晶体场强度反向变化（轻减弱36%、重增强25%），易轴转向基面，为重稀土扩散提供原子机制。
中文摘要 AI 辅助
稀土永磁体的矫顽力源于作用于局域4f电子的晶体场，然而晶界如何改变潜在的单离子哈密顿量在很大程度上仍然未知。在此，我们利用嵌入多参考电子结构计算，针对取代系列Ce、Pr、Nd、Gd、Tb和Dy，确定了Nd2Fe14B体相和晶界环境中的4f晶体场。晶界畸变在镧系元素系列中产生交叉行为：轻镧系元素的晶体场减弱高达36%，而重镧系元素的晶体场增强约25%，其中Nd标志着这一交叉点。Dy的基态二重态变得更加孤立且轴向化，而Ce则表现出塌缩的低能激发，抑制了各向异性。局域易轴从体相的c轴转向基面，表明晶界位点是磁化反转的有利成核中心。这些结果为重稀土晶界扩散提供了原子层面的基础，并为自旋-晶格模拟提供了可转移的单离子参数。
英文摘要
The coercivity of rare-earth permanent magnets originates from the crystal field acting on localized 4f electrons, yet how grain boundaries modify the underlying single-ion Hamiltonian remains largely unknown. Here we determine the 4f crystal field in bulk and grain-boundary environments of Nd2Fe14B using embedded multireference electronic-structure calculations for the substitutional series Ce, Pr, Nd, Gd, Tb, and Dy. Grain-boundary distortion produces a crossover across the lanthanide series: the crystal field weakens by up to 36% for light lanthanides but strengthens by about 25% for heavy lanthanides, with Nd marking the crossover. The ground-state doublet of Dy becomes more isolated and axial, whereas Ce exhibits a collapsed low-lying excitation that suppresses anisotropy. The local easy axis rotates from the bulk c axis toward the basal plane, identifying grain-boundary sites as favorable nucleation centers for magnetization reversal. These results provide an atomistic basis for heavy rare-earth grain-boundary diffusion and furnish transferable single-ion parameters for spin-lattice simulations.
发表机构
- Merrimack College（梅里马克学院）
- Mendelan LLC（门德兰有限责任公司）
机构由 AI 辅助整理，请以论文原文为准。
