北京科技大学邢献然研究团队的一项最新研究揭示了TbMn₆(Ge,Ga)6中表现出特殊的自发交换偏置的双层Kagome铁磁体。相关论文于2025年3月27日发表在《美国化学会杂志》上。

研究人员报告了一种新兴的2D类双层Kagome铁磁体，通过将双层间的磁相互作用减少到几乎为零。这一概念是在大块TbMn₆(Ge,Ga)₆化合物中实现的，该化合物具有分离的纯Mn Kagome晶格，只需用Ga取代Ge。具体来说，目标化合物TbMn₆Ge₅Ga₁表现出约1.6T的巨大自发交换偏置（SEB），是已知材料的两倍多。场相关中子衍射揭示了补偿铁磁（FiM）的robthemt性质，其特征是几乎三分之二的力矩被钉住，并且在高达9t的场下不可逆。通过磁和结构分析以及理论计算，课题组研究人员证明了大量的SEB与双层Kagome结构中局部robthemt和弱FiM态之间的激烈竞争有关。它们被不相称的自旋排列所稳定。双层Kagome磁铁的概念为发现2d类材料的吸引特性提供了新的机会。

据了解，操纵二维（2D）材料的层间相互作用导致了有趣的行为。将这些二维特征借用到大块材料上，可能会解锁特殊的特性。

附：英文原文

Title: Bilayer Kagome Ferrimagnet Exhibiting Exceptional Spontaneous Exchange Bias in TbMn6(Ge,Ga)6

Author: Hankun Xu, Wenjie Li, Junjie Chen, Sergii Khmelevskyi, Dmitry Khalyavin, Pascal Manuel, Chuanying Xi, Shogo Kawaguchi, Jing Chen, Wanda Yang, Qinghua Zhang, Yili Cao, Chengyi Yu, Yang Ren, Kun Lin, Xianran Xing

Issue&Volume: March 27, 2025

Abstract: Manipulating interlayer interactions in two-dimensional (2D) materials has led to intriguing behaviors. Borrowing these 2D signatures to bulk materials is likely to unlock exceptional properties. Here, we report an emergent 2D-like bilayer Kagome ferrimagnet through reducing the interbilayer magnetic interaction to nearly zero. This concept is realized within bulk TbMn6(Ge,Ga)6 compounds, characterized by an isolated and pure Mn Kagome lattice, simply by the chemical substitution of Ge with Ga. Specifically, the targeted compound TbMn6Ge5Ga1 exhibits a giant spontaneous exchange bias (SEB) of approximately 1.6 T, which is more than twice that observed in known materials. Field-dependent neutron diffraction reveals the robust nature of the compensated ferrimagnetic (FiM), characterized by almost two-thirds of the moments being pinned and irreversible under fields up to 9 T. Through magnetic and structural analysis, alongside theoretical calculations, we demonstrate that the substantial SEB is related to the intense competition between local robust and weak FiM states within the bilayer Kagome configuration, which are stabilized by an incommensurate spin arrangement. The concept of a bilayer Kagome magnet offers new opportunities for discovering attractive properties in 2D-like materials.

DOI: 10.1021/jacs.4c17505

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c17505