发表机构
University of California at Berkeley; Lawrence Berkeley National Laboratory; National Institute for Materials Science（加州大学伯克利分校; 劳伦斯伯克利国家实验室; 物质·材料研究机构）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过无接触射频反射法在双层MoSe2中观测到电子和空穴的密度调制的金属-绝缘体转变，证实了相互作用驱动的维格纳固体熔化机制，为接触受限系统提供了定量输运方法。
AI 中文摘要
当库仑相互作用主导动能时，稀薄的二维载流子会形成维格纳固体。其熔化和无序诱导的局域化都可以驱动密度调制的金属-绝缘体转变，但它们的相对作用和相互影响已争论数十年。原子级薄半导体提供了新的测试途径，因为输运和扫描隧道显微镜可以探测同一种材料，然而在相关性最强的区域，不良接触阻碍了输运测量。在此，我们引入了无接触射频反射测量法，通过电容性栅极耦合来感知薄层电阻。该方法在同一双层MoSe2器件中分辨出了电子和此前无法触及的空穴转变，这些载流子共享无序但质量不同。它们的临界密度相差四倍，但对应的库仑能与动能之比相当，而隧道显微镜在此处观察到固液共存。磁阻在每个转变处急剧峰值，反映了类似波梅兰丘克效应的场驱动维格纳固体相对于相关液体的膨胀。我们的结果证明了高质量二维半导体中相互作用驱动的转变，为接触受限系统中的定量输运开辟了道路。
英文摘要
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.
