Acoustic carrier and spin transport in transition metal dichalcogenide heterostructures

Abstract

The exciton and spin-valley properties of transition metal dichalcogenide (TMD) monolayers and heterostructures have received considerable attention of the Solid-State Physics community. The lack of inversion symmetry, spin-orbit coupling and the coupling between adjacent monolayers in these two types of structures lead to a diversity of non-trivial excitonic effects associated to many body physics. Moreover, the spin and valley degrees of freedom play a fundamental role in the optical selection rules for exciton absorption and recombination in these materials. In this project, we will investigate exciton dissociation as well as carrier and spin transport with surface acoustic waves (SAW) in different structures formed by encapsulated TMD monolayers and TMD heterostructures assembled with different materials. In monolayers, we will investigate the effect of encapsulation with hexagonal boron nitride (hBN) in the carrier mobility, dielectric screening and carrier acoustic transport. In heterostructures, we will investigate de lateral injection of carriers and the effect of the SAW strain and piezoelectric fields in the properties of optically excited interlayer excitons. We will employ different optical spectroscopy techniques like low-temperature acoustically modulated micro-photoluminescence and second harmonic generation to address fundamental properties of exciton and spin scattering mechanisms in artificially stacked two dimensional materials. (AU)