Reorientation of the stripe Phase of 2D Electrons by a Minute Density   Modulation
  Interacting two-dimensional electrons confined in a GaAs quantum well exhibit isotropic transport when the Fermi level resides in the first excited ($N=1$) Landau level. Adding an in-plane magnetic field ($B_{||}$) typically leads to an anisotropic, stripe-like (nematic) phase of electrons with the stripes oriented perpendicular to the $B_{||}$ direction. Our experimental data reveal how a periodic density modulation, induced by a surface strain grating from strips of negative electron-beam resist, competes against the $B_{||}$-induced orientational order of the stripe phase. Even a minute ($<0.25\%$) density modulation is sufficient to reorient the stripes along the direction of the surface grating. 
M. A. Mueed, Md. Shafayat Hossain, L. N. Pfeiffer, K. W. West, K. W.   Baldwin, and M. Shayegan
cond-mat.mes-hall