Xu Suheng, Li Yutao, Vitalone Rocco A, Jing Ran, Sternbach Aaron J, Zhang Shuai, Ingham Julian, Delor Milan, McIver James W, Yankowitz Matthew, Queiroz Raquel, Millis Andrew J, Fogler Michael M, Dean Cory R, Pasupathy Abhay N, Hone James, Liu Mengkun, Basov D N
Department of Physics, Columbia University, New York, NY 10027, USA.
Brookhaven National Laboratory, Upton, NY 11973, USA.
Sci Adv. 2024 Oct 25;10(43):eado5553. doi: 10.1126/sciadv.ado5553. Epub 2024 Oct 23.
Ultraclean graphene at charge neutrality hosts a quantum critical Dirac fluid of interacting electrons and holes. Interactions profoundly affect the charge dynamics of graphene, which is encoded in the properties of its electron-photon collective modes: surface plasmon polaritons (SPPs). Here, we show that polaritonic interference patterns are particularly well suited to unveil the interactions in Dirac fluids by tracking polaritonic interference in time at temporal scales commensurate with the electronic scattering. Spacetime SPP interference patterns recorded in terahertz (THz) frequency range provided unobstructed readouts of the group velocity and lifetime of polariton that can be directly mapped onto the electronic spectral weight and the relaxation rate. Our data uncovered prominent departures of the electron dynamics from the predictions of the conventional Fermi-liquid theory. The deviations are particularly strong when the densities of electrons and holes are approximately equal. The proposed spacetime imaging methodology can be broadly applied to probe the electrodynamics of quantum materials.
电荷中性的超清洁石墨烯承载着相互作用的电子和空穴的量子临界狄拉克流体。相互作用深刻影响着石墨烯的电荷动力学，这在其电子 - 光子集体模式（即表面等离激元极化激元，简称SPP）的性质中有所体现。在此，我们表明，极化激元干涉图案特别适合通过在与电子散射相称的时间尺度上跟踪时间上的极化激元干涉来揭示狄拉克流体中的相互作用。在太赫兹（THz）频率范围内记录的时空SPP干涉图案提供了极化激元群速度和寿命的无障碍读数，这些读数可以直接映射到电子谱权重和弛豫率上。我们的数据揭示了电子动力学与传统费米液体理论预测的显著偏差。当电子和空穴的密度大致相等时，这种偏差尤为强烈。所提出的时空成像方法可广泛应用于探测量子材料的电动力学。
