论文标题
通过自旋诱导的立方晶格中自旋诱导的铁电偏振来实现拓扑罗马表面的物理实现
Physical realization of topological Roman surface by spin-induced ferroelectric polarization in cubic lattice
论文作者
论文摘要
拓扑是几何学中的数学概念，已成为描述拓扑状态和相变的理想理论工具。许多拓扑概念已经在拓扑/几何不变式确定的真实或相互空间中发现了它们的物理实体，这些空间通常在可定向的表面（例如圆环和球体）上定义。自然可以找到是否可以找到更有趣的不可取向表面的物理实现。在本文中，我们表明，在立方钙钛矿氧化物AMN3CR4O12（A = LA和TB）中，自旋诱导的铁电极化集位于拓扑罗马表面上，拓扑罗马表面，这是一种不可定向的二维歧管，该表面是由向椎间盘缝制的Mobius带边缘形成的。诱导的极化可能会沿着不可定向的莫比乌斯带或可定向的盘以旋转方式在循环中传播，这取决于旋转如何通过外部磁场控制的方式演变。在实验上，极化的周期性可以是相同的，也可以是旋转磁场的两次，分别与盘和mosius条的可方向性一致。此路径依赖性拓扑磁电效应提供了一种检测表面全球几何形状并加深我们对数学和物理拓扑的理解的方法
Topology, a mathematical concept in geometry, has become an ideal theoretical tool for describing topological states and phase transitions. Many topological concepts have found their physical entities in real or reciprocal spaces identified by topological/geometrical invariants, which are usually defined on orientable surfaces such as torus and sphere. It is natural to quest whether it is possible to find the physical realization of more intriguing non-orientable surfaces. Herein, we show that the set of spin-induced ferroelectric polarizations in cubic perovskite oxides AMn3Cr4O12 (A = La and Tb) resides on the topological Roman surface, a non-orientable two-dimensional manifold formed by sewing a Mobius strip edge to that of a disc. The induced polarization may travel in a loop along the non-orientable Mobius strip or orientable disc depending on how the spin evolves as controlled by external magnetic field. Experimentally, the periodicity of polarization can be the same or the twice of the rotating magnetic field, being well consistent with the orientability of disc and Mobius strip, respectively. This path dependent topological magnetoelectric effect presents a way to detect the global geometry of the surface and deepens our understanding of topology in both mathematics and physics
