Temperature dependence of excitonic Hubbard U interaction in WS2/WSe2 moiré superlattices

Abstract

WS₂/WSe₂ moiré superlattices, formed with small twist angles, realize unique quantum phenomena such as the Hubbard effect due to periodic potential wells confining excitons. The Hubbard U interaction denotes the energy penalty for multiple excitons occupying a single well. However, most research focuses on low temperatures, neglecting thermal effects. Here, we systematically investigated temperature-dependent exciton dynamics using photoluminescence spectroscopy for precise structural and optical characterization. By controlling temperature (5–80 K), we observed a Hubbard U, with the IX₂ peak red-shifting and vanishing at 78 K, indicating that temperature-induced thermal fluctuations disrupt exciton confinement and suppress the Hubbard effect. Our findings clarify the critical impact of temperature on exciton quantum states and inform the design of moiré superlattice-based quantum devices, thus advancing applications of two-dimensional materials in quantum technology.