An electronic microemulsion phase emerging from a quantum crystal-to-liquid transition

Abstract

Strongly interacting electronic systems often exhibit a complicated phase diagram that results from the competition between different quantum ground states. One feature of these phase diagrams is the emergence of microemulsion phases, where regions of different phases self-organize across multiple length scales. The experimental characterization of these microemulsions can pose significant challenges, as the long-range Coulomb interaction microscopically mingles the competing states. Here, we observe the signatures of the microemulsion between an electronic Wigner crystal and an electron liquid in a MoSe2 monolayer using cryogenic reflectance and magneto-optical spectroscopy. We find that the transition into this microemulsion state is marked by anomalies in exciton reflectance, spin susceptibility, and umklapp scattering, establishing it as a distinct phase of electronic matter.