Two-Dimensional AXenes: A New Family of Room-Temperature d 0 Ferromagnets and Their Structural Phase Transitions

作者：Xue Jiang, Qinxi Liu, Jianpei Xing, Jijun Zhao · 发表于：The Journal of Physical Chemistry Letters · 年份：2019 · DOI：10.1021/acs.jpclett.9b03030 · 被引用次数：29 · 研究领域：2D Materials and Applications、MXene and MAX Phase Materials、Graphene research and applications

The recent discovery of two-dimensional (2D) magnetic order in monolayer CrI 3 and bilayer Fe 3 GeTe 2 has stimulated intense experimental and theoretical activities to expand the family of 2D magnets. Most 2D magnets reported to date are transition metal compounds with unpaired d electrons. Novel 2D intrinsic magnets with long-range p state coupling are also highly desirable. Here, we propose that nonstoichiometry is a feasible and universal strategy to realize long-range p electron magnetic order in 2D metal-shrouded AXenes (Na 2 N, K 2 N, and Rb 2 N), supported by our first-principles calculations. Taking K 2 N as a representative, three series of cation-deficient K 2 N (T, H, and I phases) have been predicted as stable ferromagnetic half-metal/metal with a Curie temperature of 480–1180 K. Their robust ferromagnetism is ascribed to the coexistence of carrier-mediated exchange and N–K–N superexchange interaction. Moreover, mechanical deformation can trigger reversible phase transformation by choosing their 3D layered counterpart as the intermediate phase.