库仑耦合三层石墨烯中的电可调双组分激子凝聚体
Electrically Tunable Two-Component Exciton Condensate in a Coulomb-Coupled Graphene Trilayer
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中文总结 AI 辅助
本研究通过静电栅极调控三层石墨烯载流子密度，结合实验与理论证实了具有可连续调控内部结构的双组分激子凝聚体的存在。
中文摘要 AI 辅助
多组分凝聚体具有单组分凝聚体所不具备的内部相位自由度，但其组分在固体中极少可控。本研究制备了层间隧穿可忽略的三层石墨烯，通过静电栅极可连续调控各层的载流子密度。量子电容测量表明，总填充因子为1和2时的电荷不可压缩量子霍尔态，在全层填充配置范围内均存在，并连续连接三个双层激子凝聚体极限，为三层激子态提供了证据。静态Hartree-Fock与时变Hartree-Fock计算显示，当三层均部分填充时，分别得到两个独立的有限相位刚度本征模和两个线性色散的Goldstone模；当某一层未填充时，仅剩余一个相位刚度本征模和一个线性Goldstone模。随着层间电荷转移，刚度本征模在相邻两层激子基之间连续旋转，揭示了对凝聚体模式组分的电学调控。实验与理论结果共同支持双组分激子凝聚体的识别，其内部结构可连续调控。
英文摘要
Multicomponent condensates possess internal phase degrees of freedom unavailable to a single-component condensate, yet their components are rarely controllable in solids. Here we realize a graphene trilayer with negligible interlayer tunnelling in which the layer-specific carrier densities are continuously tuned by electrostatic gating. Quantum-capacitance measurements demonstrate that charge-incompressible quantum Hall states at total filling factors 1 and 2 persist across the full range of layer-filling configurations and continuously connect the three bilayer exciton-condensate limits. This persistence provides evidence for a trilayer excitonic state. Static Hartree-Fock and time-dependent Hartree-Fock calculations yield two independent finite phase-stiffness eigenmodes and two linearly dispersing Goldstone modes, respectively, when all three layers are partially filled, whereas only one phase-stiffness eigenmode and one linear Goldstone mode remain when one layer is unfilled. The stiffness eigenmodes rotate continuously between the two adjacent-layer exciton bases as charge is transferred among the layers, revealing electrical control of the condensate-mode composition. Together, the experimental and theoretical results support the identification of a two-component exciton condensate with a continuously tunable internal structure.
