论文标题
可切换的X射线轨道角动量从人造自旋冰
Switchable X-ray Orbital Angular Momentum from an Artificial Spin Ice
论文作者
论文摘要
人工旋转冰（ASI）已被广泛研究为具有由其几何形状支配的外来特性的磁性超材料。同时，对X射线光子轨道角动量（OAM）的兴趣已迅速增长。在这里，我们表明具有编程拓扑缺陷的正方形ASI，双层脱位，将OAM授予散射的X射线。与单个位错不同，双位错不会引入磁性挫败感，并且ASI平衡其抗铁磁（AF）基态。缺陷的拓扑充电相对于结构和磁性阶的不同。因此，来自ASI的X射线衍射分别在结构和AF BRAGG条件下产生具有均匀和奇数的量子量子数的光子。 ASI的磁过渡使AF OAM梁通过温度和施加的磁场的适度变化打开和关闭。这些结果表明，ASIS可以用作可重构X射线光学元件的元信息，该光学元件可以实现电子和磁性性能的选择性探针。
Artificial spin ices (ASI) have been widely investigated as magnetic metamaterials with exotic properties governed by their geometries. In parallel, interest in X-ray photon orbital angular momentum (OAM) has been rapidly growing. Here we show that a square ASI with a programmed topological defect, a double edge dislocation, imparts OAM to scattered X-rays. Unlike single dislocations, a double dislocation does not introduce magnetic frustration, and the ASI equilibrates to its antiferromagnetic (AF) ground state. The topological charge of the defect differs with respect to the structural and magnetic order; thus, X-ray diffraction from the ASI produces photons with even and odd OAM quantum numbers at the structural and AF Bragg conditions, respectively. The magnetic transitions of the ASI allow the AF OAM beams to be switched on and off by modest variations of temperature and applied magnetic field. These results demonstrate ASIs can serve as metasurfaces for reconfigurable X-ray optics that could enable selective probes of electronic and magnetic properties.
