Charge Density Wave With Meronlike Spin Texture Induced By A Lateral Superlattice In A Two-Dimensional Electron Gas

The combined effect of a lateral square superlattice potential and the Coulomb interaction on the ground state of a two-dimensional electron gas in a perpendicular magnetic field is studied for different rational values of Gamma, the inverse of the number of flux quanta per unit cell of the external potential, at filling factor nu = 1 in Landau-level N = 0. When Landau-level mixing and disorder effects are neglected, increasing the strength W-0 of the potential induces a transition at a critical strength of W-0((c)) from a uniform and fully spin-polarized state to a two-dimensional charge density wave (CDW) with a meronlike spin texture at each maximum and minimum of the CDW. The collective excitations of this "vortex CDW" are similar to those of the Skyrme crystal that is expected to be the ground-state near filling factor nu = 1. In particular, a broken U(1) symmetry in the vortex CDWresults in an extra gapless phase mode that could provide a fast channel for the relaxation of nuclear spins. The average spin-polarization S-z changes in a continuous or discontinuous manner as W0 is increased depending on whether Gamma is an element of [ 1/2,1] or Gamma is an element of[ 0,1/2]. The phase mode and the meronlike spin texture disappear at a large value of W0 leaving as the ground state a partially spin-polarized CDW if Gamma not equal 1/2 or a spin-unpolarized CDW if Gamma = 1/2.