engleski

Polarization vectors in a 2D Wigner crystal

We analyze the polarization vectors of two acoustic modes propagating in a two-dimensional (2D) electron crystal formed above a dielectric layer (liquid He) on a metallic substrate. The electrons are delocalized in the perpendicular direction, thus forming a quasi-2D Wigner lattice. We have found that the acoustic modes are strictly polarized in the longitudinal ($L$) and transverse ($T$) direction only close to the centre of the first Brillouin zone, whereas towards the zone edge the polarization can be shifted from the $L$ and $T$ directions (depending on the propagating wave direction) up to $30^o$. We have also shown that the shape of the electron wave function has no significant influence on the polarization vectors, i.e. similar results are derived for a delocalized as well as for a strictly localized 2D Wigner crystal.

Wigner crystal; polarization vectors

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