Effect of density on quantum Hall stripe orientation in tilted magnetic fields

We investigate quantum Hall stripes under in-plane magnetic field $B_\parallel$ in a variable-density two-dimensional electron gas. At filling factor $\nu = 9/2$, we observe one, two, and zero $B_\parallel$-induced reorientations at low, intermediate, and high densities, respectively. The appearance of these distinct regimes is due to a strong density dependence of the $B_\parallel$-induced orienting mechanism which triggers the second reorientation, rendering stripes \emph{parallel} to $B_\parallel$. In contrast, the mechanism which reorients stripes perpendicular to $B_\parallel$ showed no noticeable dependence on density. Measurements at $\nu = 9/2$ and $11/2$ at the same, tilted magnetic field, allows us to rule out density dependence of the native symmetry-breaking field as a dominant factor. Our findings further suggest that screening might play an important role in determining stripe orientation, providing guidance in developing theories aimed at identifying and describing native and $B_\parallel$-induced symmetry-breaking fields.