论文标题
Haldane模型在骰子晶格上的拓扑特征：平面频段在运输特性中的作用
Topological features of Haldane model on a dice lattice: role of flat band on transport properties
论文作者
论文摘要
我们研究了Haldane模型在带状骰子晶格上的拓扑特性，该骰子晶格具有三个原子单元（称为a，b和c），并且频谱由三个频段组成，包括平坦的频带。这些频段是系统变形的，目的是研究拓扑和传输特性的演变。变形是通过跳跃各向异性引起的，并以两种不同的方式实现。在其中一个中，B和C sublattices站点之间的跳跃幅度以及A和B sublattices之间的跳跃沿特定方向变化，而在另一个方向上，A和B Sublattices的站点之间的跳跃在相同的方向上有所不同（保持B-C跳跃）。第一种情况保留了熟悉的骰子晶格的某些光谱特征，并在相图中以$ C = \ pm2 $在一定的临界变形中产生Chern绝缘裂片。拓扑特征是由色带的每个边缘的一对手性边缘模式以及在异常的霍尔电导率中观察到的高原支持支持上述情况支持的。而仅对A-B跳振幅的选择性调整会扭曲平坦带，并在系统的拓扑特性上产生重要的影响。与上面的情况相比，相图中的绝缘裂片具有不同的特征，并且在零偏置附近的霍尔电导率中观察到倾角。随着跳跃各向异性的变化，倾角会扩大，因此，情景与在异常的霍尔电导率中观察到的熟悉的高原结构相距很大。但是，在两种情况下，在两种情况下，Chern数量从$ \ pm2 $变为零以外的不连续变化到零的相位，从拓扑到零变化的相位过渡仍然是两种情况下的共同特征。
We study the topological properties of a Haldane model on a band deformed dice lattice, which has three atoms per unit cell (call them as A, B and C) and the spectrum comprises of three bands, including a flat band. The bands are systematically deformed with an aim to study the evolution of topology and the transport properties. The deformations are induced through hopping anisotropies and are achieved in two distinct ways. In one of them, the hopping amplitudes between the sites of B and C sublattices and those between A and B sublattices are varied along a particular direction, and in the other, the hopping between the sites of A and B sublattices are varied (keeping B-C hopping unaltered) along the same direction. The first case retains some of the spectral features of the familiar dice lattice and yields Chern insulating lobes in the phase diagram with $C=\pm2$ till a certain critical deformation. The topological features are supported by the presence of a pair of chiral edge modes at each edge of a ribbon and the plateaus observed in the anomalous Hall conductivity support the above scenario. Whereas, a selective tuning of only the A-B hopping amplitudes distorts the flat band and has important ramifications on the topological properties of the system. The insulating lobes in the phase diagram have distinct features compared to the case above, and there are dips observed in the Hall conductivity near the zero bias. The dip widens as the hopping anisotropy is made larger, and thus the scenario registers significant deviation from the familiar plateau structure observed in the anomalous Hall conductivity. However, a phase transition from a topological to a trivial insulating region demonstrated by the Chern number changing discontinuously from $\pm2$ to zero beyond a certain critical hopping anisotropy remains a common feature in the two cases.
