论文标题
相关的F-电子系统中的隐藏顺序和多极交换案件
Hidden order and multipolar exchange striction in a correlated f-electron system
论文作者
论文摘要
某些材料的低温阶段的顺序性质并未通过实验直接看到。这种“隐藏命令”（HO）可能会激发数十年的研究，以确定那些异国物质状态的机制。在绝缘子中，HO相源于退化的多电子状态，以可能具有高级数矩的局部f或d壳。再加上现场交换，这些时刻构成了竞争订单参数的巨大空间。在这里，我们展示了如何通过由多体企业初始力学定性方法衍生的低能汉密尔顿（Hamiltonian）充分描述的原型HO系统，Neption二氧化物NPO $ _2 $的基础秩序和磁激发。 NP $^{4+} $ ions的最低晶体场四曲线之间的相互作用诱导次生四倍订单的主要非电流级rank-odd Rank-5（Triakonkonkonkonkonkontolar）矩，从而保留NPO $ _2 $ _2 $。我们的研究还揭示了NPO $ _2 $ ho相的异常收缩背后的非常规多极交换 - 分类机制。
The nature of order in low-temperature phases of some materials is not directly seen by experiment. Such "hidden orders" (HO) may inspire decades of research to identify the mechanism underlying those exotic states of matter. In insulators, HO phases originate in degenerate many-electron states on localized f or d shells that may harbor high-rank multipole moments. Coupled by inter-site exchange, those moments form a vast space of competing order parameters. Here, we show how the ground state order and magnetic excitations of a prototypical HO system, neptunium dioxide NpO$_2$, can be fully described by a low-energy Hamiltonian derived by a many-body ab initio force-theorem method. Superexchange interactions between the lowest crystal-field quadruplet of Np$^{4+}$ ions induce a primary non-collinear order of time-odd rank-5 (triakontadipolar) moments with a secondary quadrupole order preserving the cubic symmetry of NpO$_2$. Our study also reveals an unconventional multipolar exchange-striction mechanism behind the anomalous volume contraction of the NpO$_2$ HO phase.
