Zero-Field Wigner Solids in Ultra-Thin Films of Cadmium Arsenide

The Wigner crystal is the ground state of a two-dimensional electron system in the low-density limit, where Coulombic repulsion between electrons overwhelms the kinetic energy and freezes them into a lattice. In this talk, we report transport signatures of electron- and hole-type Wigner solids in ultra-thin films of Cd₃As₂near the topological transition at zero magnetic field. Highly non-linear current-voltage behavior and voltage fluctuations arise from the pinned solid sliding over the disorder potential under finite bias. Hysteresis in the I-V appears due to domain motion, which disappears simultaneously with the aforementioned signatures above a critical temperature. Furthermore, a small magnetic field destroys the Wigner solids, in contrast to most other reports. We discuss their emergence in the context of spatial inversion asymmetry and spin-orbit coupling.