Crystallization of the transdimensional electron liquid

Wigner crystallization of free electrons at room temperature (T) is explored for a new class of metallic ultrathin transdimensional (TD) materials with properties controlled by their thickness [1]. TD is the regime in between 2 and 3 dimensions [2] that allows one to probe the fundamental properties of solid-state materials as they evolve from the 3D case of bulk materials to the 2D case of atomically thin (quantum confined) nanomaterial films of the same chemical composition. Here, we develop a theory to generalize the Platzman-Fukyuama model of Wigner crystal formation in free-standing 2D electron gas systems [3], to the practical case of the TD plasmonic films. Our calculations of the critical electron density, temperature and melting curve show that by reducing the material thickness one can Wigner-crystallize free electrons at room T to get them pinned onto a 2D triangular lattice of a supersolid inside of the crystalline material. Such a solid melts and freezes reversibly with increase and decrease of electron doping or T, whereby its resistivity behaves opposite to the free electron gas model predictions. [1]I.V.Bondarev, et al., ArXiv: 2503.05165 (2025); [2]A.Boltasseva & V.M.Shalaev, ACS Phot. 6, 1 (2019); [3]P.M.Platzman & H.Fukuyama, PRB 10, 3150 (1974).