Observation of an electronic microemulsion phase emerging from a quantum crystal-to-liquid transition

TL;DR

This study reports the experimental observation of a microemulsion phase in a 2D electronic system, revealing a new state that emerges from a quantum crystal-to-liquid transition driven by strong Coulomb interactions.

Contribution

First experimental detection of an electronic microemulsion phase in a 2D material, providing insights into complex correlated electron states with strong Coulomb interactions.

Findings

Signatures of the microemulsion phase observed in exciton reflectance, spin susceptibility, and Umklapp scattering.

The phase transition is marked by anomalies indicating a distinct electronic state.

Elucidates the physics of novel correlated electron states in 2D materials.

Abstract

Strongly interacting electronic systems possess rich phase diagrams resulting from the competition between different quantum ground states. A general mechanism that relieves this frustration is the emergence of microemulsion phases, where regions of different phase self-organize across multiple length scales. The experimental characterization of these phases often poses significant challenges, as the long-range Coulomb interaction microscopically mingles the competing states. Here, we use cryogenic reflectance and magneto-optical spectroscopy to observe the signatures of the mixed state between an electronic Wigner crystal and an electron liquid in a MoSe2 monolayer. We find that the transit 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. Our study of the two-dimensional electronic microemulsion phase elucidates the physics of novel correlated electron states with strong Coulomb interactions.