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 $W_{0}^{\left( c\right) },$ 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 \textquotedblleft vortex-CDW\textquotedblright\ are similar to those of the Skyrme crystal that is expected to be the ground state \textit{near} filling factor $\nu =1$. In particular, a broken U(1) symmetry in the vortex-CDW results 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 $W_{0}$ is increased depending on whether $\Gamma \in \left[ 1/2,1\right] $ or $\Gamma\in \left[ 0,1/2\right]$.