OPTICAL BRANCH OF MAGNETOPHONONS IN A DOUBLE-LAYER WIGNER CRYSTAL

The Wigner crystal of electrons in a couple of two-dimensional layers in semiconductor structures is shown to form a two-component lattice and to possess a specific excitation, namely, an optical phonon mode. The calculated frequencies of optical magnetophonons in the magnetically frozen double-layer Wigner crystal demonstrate exponential dependence on the interlayer spacing and electronic density, and we guess that their observation can give a direct indication of the crystalline ordering in the magnetic freeze-out regime.