arXiv subjects

Maxime Mauguet

Publications and source records attributed to Maxime Mauguet.

2 recordsLinked to original sources

arXiv2026

Sub-nm range momentum-dependent exciton transfer from a 2D semiconductor to graphene

Heterostructures made from atomically thin semiconductors (here MoSe$_2$) and graphene are uniquely poised to investigate photoinduced charge and energy transfer in the 2D limit. Here, using picosecond time-resolved photoluminescence spectroscopy at cryogenic temperatures on two types of MoSe$_2$/graphene heterostrutures, we unveil key features of the underlying mechanisms. First, the shortening of the MoSe$_2$ bright exciton lifetime is marginally affected by the number of graphene layers to which MoSe$_2$ is coupled. Second, exciton transfer vanishes when a sub-nm thick spacer of hexagonal boron nitride decouples MoSe$_2$ from graphene. These results indicate that charge tunneling govern bright exciton relaxation in MoSe$_2$/graphene and that longer-range, F\"orster-type energy transfer (FRET) does not affect bright excitons. However, sub-ps FRET to graphene accelerates the relaxation of ``hot'' excitons formed upon optical excitation, leading to photoluminescence quenching factors that exceed expectations based on the shortening of the bright exciton lifetime. Our work has direct implications for energy harvesting and funneling using van der Waals heterostructures.

cond-mat.mes-hall↗

arXiv2026

Emission Dynamics of Rydberg Excitons in $\mathbf{\mathrm{Cu_2O}}$: Distinguishing Second Harmonic Generation from Secondary Emission

Rydberg excitons in $\mathrm{Cu_2O}$ simultaneously give rise to two very different optical responses under resonant two-photon excitation: a coherent second-harmonic signal mediated by the excitonic second order susceptibility tensor $\chi^{(2)}$, and a secondary emission originating from the radiative decay of real exciton populations. Distinguishing these two channels is essential for interpreting nonlinear and quantum-optical experiments based on high-$n$ states, yet their temporal, spectral, and power-dependent signatures often overlap. Here we use time-resolved resonant two-photon excitation to cleanly separate SHG and SE and to map how each depends on $n$, temperature, excitation power, and crystal quality. This approach reveals the markedly different sensitivities of the two processes to phonons, defects, and many-body effects, and establishes practical criteria for identifying SE and SHG in a wide range of experimental conditions. Our results provide a unified framework for interpreting emission from Rydberg excitons and offer guidelines for future studies aiming to exploit their nonlinear response and long-range interactions.

cond-mat.quant-gas↗