Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 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.

17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph