Imaging Intermediate Melting Phases of Dual Magnetic-Field-Stabilized Wigner Crystals

TL;DR

This study visualizes the melting processes of dual Wigner crystals in monolayer VCl3, revealing distinct intermediate phases and providing insights into their microscopic melting pathways under high magnetic fields.

Contribution

It uncovers the existence of two coexisting Wigner crystals with different melting behaviors and intermediate phases, advancing understanding of electron crystallization and melting in two-dimensional systems.

Findings

One Wigner crystal exhibits a record-high critical temperature and melts via a nematic phase.

The other Wigner crystal shows an anomalous electron liquid phase during melting.

First-principles calculations support the formation of dual Wigner crystals through band-selective electron occupations.

Abstract

The competition between Coulomb repulsion and kinetic energy in correlated systems can allow electrons to crystallize into Wigner solids. Despite researches across diverse two-dimensional Wigner platforms, the microscopic melting processes through possible intermediate phases remains largely unknown. Here, we present the visualization of electron-lattice melting in monolayer VCl3 on graphite, where two Wigner crystals coexist with markedly different critical temperatures Tc and lattice periods as stabilized by high magnetic field. One Wigner crystal possesses both record-high Tc and electron density, and undergoes melting through an intermediate nematic phase upon decreasing magnetic field. In contrast, the other Wigner crystal with a lower Tc yields a different intermediate phase during melting, exhibiting an anomalous electron liquid with an energy-independent modulation period. First-principles calculations corroborate the band-selective occupations of interface-transferred electrons in the formation of dual Wigner crystals. Our atomically resolved intermediate phases provide crucial insights into the microscopic melting pathways of Wigner crystals, enabling a phase diagram parameterized by both quantum and thermal fluctuations.