论文标题
四边形石墨烯中的螺旋边缘状态和量子相变
Helical Edge States and Quantum Phase Transitions in Tetralayer Graphene
论文作者
论文摘要
带有自旋摩托锁的螺旋导体是Majorana费米子的有前途的平台。在这里，我们报告观察两个拓扑不同的相位，这些阶段支撑着螺旋边缘状态，中性的中性伯纳尔堆积的三边形石墨烯中的霍尔杆和科比诺几何形状。随着磁场B和平面外位移场d的变化，我们观察到一个相图，该相图分别由绝缘相和两个金属相组成，分别具有0、1和2螺旋边缘状态。这些阶段是由将其电导与自旋极化平台相关的理论模型所解释的。它们之间的过渡是由层间跳，静电和交换相互作用能量之间的竞争引起的。我们的工作突出了复杂的竞争对称性和几层石墨烯中丰富的量子阶段。
Helical conductors with spin-momentum locking are promising platforms for Majorana fermions. Here we report observation of two topologically distinct phases supporting helical edge states in charge neutral Bernal-stacked tetralayer graphene in Hall bar and Corbino geometries. As the magnetic field B and out-of-plane displacement field D are varied, we observe a phase diagram consisting of an insulating phase and two metallic phases, with 0, 1 and 2 helical edge states, respectively. These phases are accounted for by a theoretical model that relates their conductance to spin-polarization plateaus. Transitions between them arise from a competition among inter-layer hopping, electrostatic and exchange interaction energies. Our work highlights the complex competing symmetries and the rich quantum phases in few-layer graphene.
