Abstract

Moiré potentials in two dimensional materials have been proven to be of fundamental importance to fully understand the electronic structure of van der Waals heterostructures, from superconductivity to correlated excitonic states. However, understanding how the moiré phonons, so-called phasons, affect the properties of the system still remains an uncharted territory. In this work, we demonstrate how phasons are integral to properly describe and understand low temperature interlayer exciton diffusion in WS₂/WSe₂ heterostructure. We perform photoluminescence (PL) spectroscopy to understand how the coupling between the layers, affected by their relative orientation, impacts on the excitonic properties of the system. Samples fabricated with stacking angle of 0° and 60° are investigated taking into account the stacking angle dependence of the two common moiré potential profiles. Additionally, we present spatially and time-resolved exciton diffusion measurements, looking at the photoluminescence emission in a temperature range from 30 K to 250 K. An accurate potential for the two configurations is computed via density functional theory (DFT) calculations. Finally, we perform molecular dynamics simulation in order to visualize the phasons’ motion, estimating the phason speed at different temperatures, providing novel inside into the mechanics of exciton propagation at low temperatures that cannot be explained within the frame of classical exciton diffusion alone

Abstract

Moiré potentials in two dimensional materials have been proven to be of fundamental importance to fully understand the electronic structure of van der Waals heterostructures, from superconductivity to correlated excitonic states. However, understanding how the moiré phonons, so-called phasons, affect the properties of the system still remains an uncharted territory. In this work, we demonstrate how phasons are integral to properly describe and understand low temperature interlayer exciton diffusion in WS₂/WSe₂ heterostructure. We perform photoluminescence (PL) spectroscopy to understand how the coupling between the layers, affected by their relative orientation, impacts on the excitonic properties of the system. Samples fabricated with stacking angle of 0° and 60° are investigated taking into account the stacking angle dependence of the two common moiré potential profiles. Additionally, we present spatially and time-resolved exciton diffusion measurements, looking at the photoluminescence emission in a temperature range from 30 K to 250 K. An accurate potential for the two configurations is computed via density functional theory (DFT) calculations. Finally, we perform molecular dynamics simulation in order to visualize the phasons’ motion, estimating the phason speed at different temperatures, providing novel inside into the mechanics of exciton propagation at low temperatures that cannot be explained within the frame of classical exciton diffusion alone

Abstract

Moiré potentials in two dimensional materials have been proven to be of fundamental importance to fully understand the electronic structure of van der Waals heterostructures, from superconductivity to correlated excitonic states. However, understanding how the moiré phonons, so-called phasons, affect the properties of the system still remains an uncharted territory. In this work, we demonstrate how phasons are integral to properly describe and understand low temperature interlayer exciton diffusion in WS₂/WSe₂ heterostructure. We perform photoluminescence (PL) spectroscopy to understand how the coupling between the layers, affected by their relative orientation, impacts on the excitonic properties of the system. Samples fabricated with stacking angle of 0° and 60° are investigated taking into account the stacking angle dependence of the two common moiré potential profiles. Additionally, we present spatially and time-resolved exciton diffusion measurements, looking at the photoluminescence emission in a temperature range from 30 K to 250 K. An accurate potential for the two configurations is computed via density functional theory (DFT) calculations. Finally, we perform molecular dynamics simulation in order to visualize the phasons’ motion, estimating the phason speed at different temperatures, providing novel inside into the mechanics of exciton propagation at low temperatures that cannot be explained within the frame of classical exciton diffusion alone

Abstract

Moiré potentials in two dimensional materials have been proven to be of fundamental importance to fully understand the electronic structure of van der Waals heterostructures, from superconductivity to correlated excitonic states. However, understanding how the moiré phonons, so-called phasons, affect the properties of the system still remains an uncharted territory. In this work, we demonstrate how phasons are integral to properly describe and understand low temperature interlayer exciton diffusion in WS₂/WSe₂ heterostructure. We perform photoluminescence (PL) spectroscopy to understand how the coupling between the layers, affected by their relative orientation, impacts on the excitonic properties of the system. Samples fabricated with stacking angle of 0° and 60° are investigated taking into account the stacking angle dependence of the two common moiré potential profiles. Additionally, we present spatially and time-resolved exciton diffusion measurements, looking at the photoluminescence emission in a temperature range from 30 K to 250 K. An accurate potential for the two configurations is computed via density functional theory (DFT) calculations. Finally, we perform molecular dynamics simulation in order to visualize the phasons’ motion, estimating the phason speed at different temperatures, providing novel inside into the mechanics of exciton propagation at low temperatures that cannot be explained within the frame of classical exciton diffusion alone