Quantum Hall drag of exciton condensate in graphene
Quantum Hall drag of exciton condensate in graphene
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DOI：
10.1038/nphys4116
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发表时间：
2017-08-01
期刊：
影响因子：
19.6
通讯作者：
Kim, Philip
中科院分区：
文献类型：
--
作者：
Liu, Xiaomeng;Watanabe, Kenji;Kim, Philip
激子凝聚体是受库仑相互作用(1，2)约束的电子和空穴对的玻色-爱因斯坦凝聚体。在强磁场作用下的双电子层(EDL)中，一层中的填充Landau态与另一层中的空态结合形成激子凝聚态(3-9)。本文报道了由六方氮化硼隔开的双层石墨烯EDL中的激子凝聚。一层石墨烯中的驱动电流在另一层中产生接近量子化的霍尔电压，导致相干激子输运(4，6)。由于原子薄介质上的库仑耦合很强，石墨烯中的量子霍尔阻力出现在比以前在GaAsEDL中观察到的温度高十倍的温度。密度和位移场的大范围可调使得能够探索具有不同填充因子和内部量子自由度的跨朗道能级的玻色-爱因斯坦凝聚体的丰富相图。观察到的强激子凝聚为研究各种多体激子相提供了机会。
An exciton condensate is a Bose-Einstein condensate of ;electron and hole pairs bound by the Coulomb interaction(1,2). In an electronic double layer (EDL) subject to strong magnetic fields, filled Landau states in one layer bind with empty states of the other layer to form an exciton condensate(3-9). Here we report exciton condensation in a bilayer graphene EDL separated by hexagonal boron nitride. Driving current in one graphene layer generates a near-quantized Hall voltage in the other layer, resulting in coherent exciton transport(4,6). Owing to the strong Coulomb coupling across the atomically thin dielectric, quantum Hall drag in graphene appears at a temperature ten times higher than previously observed in a GaAs EDL. The wide-range tunability of densities and displacement fields enables exploration of a rich phase diagram of Bose-Einstein condensates across Landau levels with different filling factors and internal quantum degrees of freedom. The observed robust exciton condensation opens up opportunities to investigate various many-body exciton phases.