Ambipolar metal-insulator transition in bilayer MoSe2

Ha-Leem Kim; Hyungbin Lim; Terry Wu; Amogh Y. Waghmare; Garima Gupta; Takashi Taniguchi; Kenji Watanabe; Archana Raja; Eric Y. Ma; Feng Wang

arXiv · 2610.09036

Ambipolar metal-insulator transition in bilayer MoSe2

Ha-Leem Kim·Hyungbin Lim·Terry Wu·Amogh Y. Waghmare·Garima Gupta·Takashi Taniguchi·Kenji Watanabe·Archana Raja·Eric Y. Ma·Feng Wang

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Abstract

When Coulomb interactions dominate kinetic energy, dilute two-dimensional carriers form a Wigner solid. Both its melting and disorder-driven localization can drive density-tuned metal-insulator transitions, but their relative roles and interplay have been debated for decades. Atomically thin semiconductors offer a new test because transport and scanning tunneling microscopy can probe the same material, yet poor contacts impede transport where correlations are strongest. Here we introduce contact-free radio-frequency reflectometry that senses sheet resistance through capacitive gate coupling. It resolves the electron and previously inaccessible hole transitions in the same bilayer MoSe2 device, whose carriers share disorder but not mass. Their critical densities differ fourfold yet correspond to comparable Coulomb-to-kinetic-energy ratios, where tunneling microscopy finds solid-liquid coexistence. Magnetoresistance peaks sharply at each transition, reflecting a Pomeranchuk-like, field-driven expansion of the Wigner solid against the correlated liquid. Our results demonstrate interaction-driven transitions in high-quality two-dimensional semiconductors, opening quantitative transport in contact-limited systems.

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Ha-Leem Kim, Hyungbin Lim, Terry Wu, Amogh Y. Waghmare, Garima Gupta, Takashi Taniguchi, Kenji Watanabe, Archana Raja, Eric Y. Ma, Feng Wang. 2026-10-06. Ambipolar metal-insulator transition in bilayer MoSe2. https://arxiv.org/abs/2610.09036

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