论文标题
孤立的平坦带的异常水平的几何表征
Geometric characterization of anomalous Landau levels of isolated flat bands
论文作者
论文摘要
根据Onsager的半经典量化规则，频带的Landau水平由零磁场处的上和下带边界界定。但是，有两个值得注意的系统，Landau级别的光谱违反了这种期望，包括具有奇异带交叉的拓扑带和扁平带，其波浪功能具有一些奇异性。在这里，我们介绍了一类不同的平面系统，尽管相关的波函数是非发挥作用，但在零场能量边界内出现了异常的Landau级别扩散（LLS）。孤立的平谱带的异常LLS由测量多条带的波功能几何形状的交叉浆果连接来控制。我们还发现，对称性对平面频段的LLS构成了强大的限制。我们的工作表明，孤立的平坦带是研究波功能几何形状在描述固体磁反应中的基本作用的理想系统。
According to the Onsager's semiclassical quantization rule, the Landau levels of a band are bounded by its upper and lower band edges at zero magnetic field. However, there are two notable systems where the Landau level spectra violate this expectation, including topological bands and flat bands with singular band crossings, whose wave functions possess some singularities. Here, we introduce a distinct class of flat band systems where anomalous Landau level spreading (LLS) appears outside the zero-field energy bounds, although the relevant wave function is nonsingular. The anomalous LLS of isolated flat bands are governed by the cross-gap Berry connection that measures the wave-function geometry of multi bands. We also find that symmetry puts strong constraints on the LLS of flat bands. Our work demonstrates that an isolated flat band is an ideal system for studying the fundamental role of wave-function geometry in describing magnetic responses of solids.
