通过先进机器学习引导框架发现新型磁性Y-Mn-B化合物
Discovery of novel magnetic Y-Mn-B compounds via advanced machine learning guided framework
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中文总结 AI 辅助
本研究开发机器学习辅助发现框架，筛选出新型稳定/亚稳Y-Mn-B硼化物，发现Mn链相保留可观磁矩与铁磁有序，证实过渡金属取代可恢复磁性，为新型稀土永磁材料设计提供新路径。
中文摘要 AI 辅助
稀土过渡金属硼化物为永磁体设计提供了关键的结构基元；然而，这些组成相空间中的富锰区域在很大程度上仍未被探索。在本研究中，我们开发了一种先进的机器学习辅助发现框架，用于探索Y-Mn-B三元体系。我们从数据库中已知结构生成的超过一百万个假想结构出发，首先应用图神经网络预测材料稳定性以筛选出有潜力的候选结构，随后使用机器学习原子间势对其结构进行弛豫，最后通过第一性原理计算验证结果。我们确定了5种稳定和近稳定的Y-Mn-B相，以及61种形成能相对于三元凸包在100 meV/原子以内的亚稳化合物。其中，Y2Mn7B7和YMn4B4在结构上类似于此前合成的$R_{1+ε}Fe_4B_4$一维无公度复合链化合物。与已报道的Fe磁矩被强烈抑制的情况形成鲜明对比的是，我们的第一性原理计算显示，预测的Mn链相保留了相当大的局部Mn磁矩（约1.1 $μ_B$），并且具有有利的铁磁有序性。电子结构分析阐明了磁矩恢复的微观起源，即由类斯托纳不稳定性驱动的增强交换劈裂。我们还进行了系统的Mn-Fe取代研究，以证实从Fe到Mn的热力学连续性以及宏观磁化强度的单调增强。这些发现表明，在一维硼化物家族中进行有针对性的过渡金属取代可以恢复过渡金属磁性，为设计新型磁性稀土过渡金属硼化物提供了一条物理上可解释的途径。
英文摘要
Rare-earth transition-metal borides offer critical structural motifs for permanent-magnet design; however, the manganese-rich regions within these compositional phase spaces remain largely unexplored. In this work, we develop an advanced machine-learning-assisted discovery framework to explore Y-Mn-B ternary system. Starting from over one million hypothetical structures generated from known structures in databases, we filtered promising candidates by first applying graph neural networks to predict material stability, then using machine-learning-interatomic-potential to relax their structures, and finally validating the results with first-principles calculations. We identify 5 stable and near-stable Y-Mn-B phases along with 61 metastable compounds with the formation energy within 100 meV/atom with respect to the ternary convex hull. Among them, Y2Mn7B7 and YMn4B4 are structurally analogous to the previously synthesized $R_{1+ε}Fe_4B_4$ 1D incommensurate composite chain compounds. In striking contrast to the strongly suppressed Fe moments reported, our first-principles calculations reveal that the predicted Mn-chain phases preserve sizable local Mn moments (approximately 1.1 $μ_B$) and favored ferromagnetic ordering. Electronic structure analyses elucidate the microscopic origin of moment recovery via an enhanced exchange splitting driven by a Stoner-like instability. We also perform systematic Mn-Fe substitution to confirm the thermodynamic continuity and a monotonic enhancement of the macroscopic magnetization, from Fe to Mn. These findings indicate that targeted transition-metal substitution within a one-dimensional boride family can recover transition-metal magnetism, offering a physically interpretable route for designing new magnetic rare-earth transition-metal borides.
