Spring 2023 Physics Colloquium: Many-body and Electron-phonon Interactions in Two-Dimensional Materials

When

3 to 4 p.m., Jan. 27, 2023

Where

Vasili Perebeinos, University at Buffalo

Abstract: Quantum information technology requires a solid-state materials platform and simulation tools [1] for building scalable devices. Atomically thin two-dimensional materials are direct bandgap semiconductors with a rich interplay of the valley and spin degrees of freedom, which offer the potential for such technologies. A strong Coulomb interaction leads to tightly bound electron-hole pairs or excitons and two-electrons one-hole quasiparticles or trions. We solve the two-particle and three-particle problems for the wavefunctions for excitons and trions in the basis set of the model Hamiltonian for single particles. The calculated linear absorptions [2], photoluminescence spectra [3], and polariton spectra [4] as a function of doping and temperature explain the experimental data in 2D monolayers and predict novel spectroscopic features [5] due to the many-body Coulomb interactions. Excitons qualitatively change the nonlinear dynamics leading, in particular, to a considerable enhancement of the second harmonic generation signal and angular polarization diagram depending on the driving strength and the type of the exciton state [6]. Finally, I will discuss the potential of graphene as a quantum phonon sensor down to a single phonon level [7] via remote electron-phonon scattering [8] in an adjacent boron nitride substrate. This material is based upon work supported by the Air Force Office of Scientific Research under award number FA9550-22-1-0312.

[1] Semenenko et. al, AVS Quantum Sci. 4, 012002 (2022)

[2] Zhumagulov et. al, Phys. Rev. B 101, 245433 (2020)

[3] Zhumagulov et. al, J. Chem. Phys. 153, 044132 (2020)

[4] Zhumagulov et. al, npj. Computational Materials 8, 1, (2022)

[5] Zhumagulov, et. al, Nanomaterials 12, 3728 (2022)

[6] Zhumagulov, et. al, Phys Rev. B 105, 115436 (2022)

[7] Kefayati, et. al., Phys Rev. B 106, 155415 (2022)

[8] Tan, et. al, Phys. Rev. Lett. 128, 206602 (2022

In-Person Only. Refreshments served at 2:45PM in PAS 218