Reentrant Melting of a Classical Quasi-One-Dimensional Wigner Crystal on the Surface of Liquid Helium

Abstract

We present transport measurements of electrons on the surface of liquid helium confined to a microscopic channel, the effective width of which can be controlled electrostatically. Above 1 K the electron system is liquid-like and the conductance varies smoothly with the channel width. At lower temperatures the system forms a classical quasi-one-dimensional Wigner crystal ( WC). Close to the WC melting temperature, the current oscillates as the channel width is varied, due to reentrant melting as recently reported [H. Ikegami, H. Akimoto, D. G. Rees, and K. Kono: Phys. Rev. Lett. 109 ( 2012) 236802]. In the WC regime we observe Bragg-Cherenkov ripplon scattering, a signature of strong spatial electron order, for both the widely open channel and the single electron chain.