Photoinduced modulation of the excitonic resonance via coupling with coherent phonons in a layered semiconductor

Abstract

The light-mediated interaction of fermionic and bosonic excitations governs the optoelectronic properties of condensed matter systems. In photoexcited semiconductors, the coupling of electron-hole pairs (excitons) to coherent optical phonons enables a modulation of the excitonic resonance that is phase-locked to the frequency of the coupled vibrational mode. Moreover, due to the Coulombic nature of excitons, their dynamics are sensitive to transient changes in the screening by the photoexcited carriers. Interestingly, the effect of photoinduced screening on the transient optical signal originating from the exciton dynamics coupled to phonons is not yet established. By

Ultrafast charge carrier and exciton dynamics in an excitonic insulator probed by time-resolved photoemission spectroscopy

“…Towards this goal, ultrafast spectroscopy techniques have further proven to offer a powerful probe. The approach is based on the optical excitation of the system's ground state followed by the determination of the relaxation pathways of the electronic, excitonic and structural degrees of freedom on the relevant time and energy scales [39,40,41,42,43,44]. It is important to note that the screening of the Coulomb interaction changes upon photoexcitation of quasiparticles in the system.…”

Surface acoustic wave induced phenomena in two-dimensional materials

“…In addition, coherent phonons in 2D materials could be induced through pumping by intense laser and magnetic fields. [192][193][194][195][196][197] The resonant optical excitation of infrared-active lattice vibrations is feasible to induce targeted structural deformations in 2D materials. 198 In 2016, the temporal dynamics of coherent lattice vibration modes in mono-and few-layer WSe 2 flakes was realized by performing time-resolved transmission measurements.…”

Real-time non-adiabatic dynamics in the one-dimensional Holstein model: Trajectory-based vs exact methods

“…13 Here, such excitations can couple to electrons and influence the electronic properties. For example, exciton-phonon coupling [17][18][19][20][21][22] in semiconductors affects exciton mobilities, the phononbottleneck mechanism reduces energy loss of hot carriers, [23][24][25][26][27] and phonon-magnon scattering 28,29 induced by electronphonon coupling can lead to ultrafast demagnetization, 30 to mention a few examples. Clearly, there is an increasing interest in the theoretical description of such multi-component systems involving bosons, also in view of recent ultrafast dynamics experiments, [31][32][33] where, for example, light excitations in electron-phonon coupled systems have been claimed to en-hance superconductivity [34][35][36][37][38][39][40] or where phase transitions to a charge-density-wave phase [41][42][43] or a metal-insulator structural phase transition 44 can be driven.…”