Transport properties of two-dimensional Wigner solid on free surface of liquid 3He-4He mixtures

The Wigner solid (WS) transport over dilute solutions of He-3 in He-4 is theoretically studied in a wide range of temperatures. It is shown that for solution concentrations x greater than or similar to 1%, the WS mobility should be limited by bulk He-3 quasiparticle reflection from the sublattice of surface dimples. The formation of a surface layer of He-3 atoms affects the WS resistivity in two different ways. First, it increases the depth of surface dimples and the kinetic friction with cooling. At the same time, it introduces the unusual diffusive reflection for bulk quasiparticles at the free surface that strongly reduces the kinetic friction, as compared with the case of specular reflection. The analysis presented indicates that the WS can be used as a sensitive probe for the bulk and surface He-3 impurity subsystems.