Wagner Koloman, Wietek Edith, Ziegler Jonas D, Semina Marina A, Taniguchi Takashi, Watanabe Kenji, Zipfel Jonas, Glazov Mikhail M, Chernikov Alexey
Department of Physics, University of Regensburg, Regensburg D-93053, Germany.
Ioffe Institute, 194021 St. Petersburg, Russia.
Phys Rev Lett. 2020 Dec 31;125(26):267401. doi: 10.1103/PhysRevLett.125.267401.
We experimentally demonstrate dressing of the excited exciton states by a continuously tunable Fermi sea of free charge carriers in a monolayer semiconductor. It represents an unusual scenario of two-particle excitations of charged excitons previously inaccessible in conventional material systems. We identify excited state trions, accurately determine their binding energies in the zero-density limit for both electron- and hole-doped regimes, and observe emerging many-body phenomena at elevated doping. Combining experiment and theory we gain access to the intra-exciton coupling facilitated by the interaction with free charge carriers. We provide evidence for a process of autoionization for quasiparticles, a unique scattering pathway available for excited states in atomic systems. Finally, we demonstrate a complete transfer of the optical transition strength from the excited excitons to dressed Fermi-polaron states as well as the associated light emission from their nonequilibrium populations.
我们通过实验证明了在单层半导体中，由连续可调谐的自由电荷载流子费米海对激发的激子态进行修饰。这代表了一种在传统材料系统中以前无法实现的带电激子双粒子激发的特殊情况。我们识别出激发态的三激子，精确确定了它们在电子掺杂和空穴掺杂体系零密度极限下的结合能，并观察到在高掺杂时出现的多体现象。结合实验和理论，我们得以了解与自由电荷载流子相互作用所促进的激子内耦合。我们为准粒子的自电离过程提供了证据，这是原子系统中激发态可用的独特散射途径。最后，我们展示了光学跃迁强度从激发的激子完全转移到修饰后的费米极化子态，以及来自其非平衡态群体的相关发光。
