ORIENTATIONAL ORDER AND DEPINNING OF THE DISORDERED ELECTRON-SOLID

Two-dimensional classical electron solids under the influence of modulation-doped impurities are studied by using a molecular dynamics method. We find that in the strong disorder limit the ground state configuration contains both isolated dislocations and disclinations, whereas in the weak disorder regime only dislocations are present. We show, via continuum elasticity theory, that the ground state of the lattice should be unstable against a proliferation of free disclinations above a critical dislocation density. Associated with this, the behavior of the depinning electric field changes.