论文标题
在kagome晶格上由远程库仑驱动驱动的环电荷电荷密度波
Loop-current charge density wave driven by long-range Coulomb repulsion on the kagome lattice
论文作者
论文摘要
最新的基于钒的非磁性Kagomé金属的实验$ a $ v $ _3 $ _3 $ _5 $（$ a = $ a = $ k，rb，cs）揭示了在电荷密度波（CDW）有序状态下可能自发的时间反向对称性（TRS）。循环电流的长期量子顺序被建议作为TRS破裂状态的候选者。但是，由于电子相关性而引起的环电流CDW出现的微观模型仍然缺乏。在这里，我们计算了Van Hove填充物附近的Kagomé晶格上的真实和假想键订单的敏感性，并揭示了下一个最新的最邻居的库仑抑制的重要性$ v_2 $ v_2 $在触发不稳定性的情况下对假想债券的订购CDW的不稳定性。然后研究了Kagomé晶格上的混凝土有效的单轨$ T $ - $ V_1 $ - $ V_2 $型号，其中$ t $和$ v_1 $是最近尼克堡债券的跳跃和库仑的排斥。我们获得了平均场地状态，分析其属性，并确定v_1 $ $ v_1 $和$ v_2 $在van Hove填充的飞机中的相图。 $ V_1 $主导的区域由$ 2A_0 \ times 2A_0 $实用CDW绝缘子与david（ISD）债券配置倒数。实际上，增加$ v_2 $确实可以驱动从ISD到稳定的环电流绝缘子的一阶过渡，这些绝缘子表现出四种可能的当前模式的不同拓扑特性，从而导致轨道Chern绝缘子。然后，我们将这些结果从范霍夫填充物中扩展出来，并表明电子掺杂有助于稳定环电流，并产生掺杂的轨道Chern绝缘子，并具有紧急的Chern Fermi口袋，带有大浆果曲率和轨道磁矩。我们的发现为打破Kagomé超导体的正常状态的平均场水平的环流金属提供了一个混凝土模型。
Recent experiments on vanadium-based nonmagnetic kagomé metals $A$V$_3$Sb$_5$ ($A=$ K, Rb, Cs) revealed evidence for possible spontaneous time-reversal symmetry (TRS) breaking in the charge density wave (CDW) ordered state. The long-sought-after quantum order of loop currents has been suggested as a candidate for the TRS breaking state. However, a microscopic model for the emergence of the loop-current CDW due to electronic correlations is still lacking. Here, we calculate the susceptibility of the real and imaginary bond orders on the kagomé lattice near van Hove filling, and reveal the importance of next-nearest-neighbor Coulomb repulsion $V_2$ in triggering the instability toward imaginary bond ordered CDW. The concrete effective single-orbital $t$-$V_1$-$V_2$ model on the kagomé lattice is then studied, where $t$ and $V_1$ are the hopping and Coulomb repulsion on the nearest-neighbor bonds. We obtain the mean-field ground states, analyze their properties, and determine the phase diagram in the plane spanned by $V_1$ and $V_2$ at van Hove filling. The region dominated by $V_1$ is occupied by a $2a_0 \times 2a_0$ real CDW insulator with the inverse of Star-of-David (ISD) bond configuration. Increasing $V_2$ indeed drives a first-order transition from ISD to stabilized loop-current insulators that exhibit four possible current patterns of different topological properties, leading to orbital Chern insulators. We then extend these results away from van Hove filling and show that electron doping helps the stabilization of loop currents, and gives rise to doped orbital Chern insulators with emergent Chern Fermi pockets carrying large Berry curvature and orbital magnetic moment. Our findings provide a concrete model realization of the loop-current Chern metal at the mean-field level for the TRS breaking normal state of the kagomé superconductors.
