Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Corner overgrowth: Bending a high mobility two-dimensional electron
  system by 90 degrees   Introducing an epitaxial growth technique called corner overgrowth, we
fabricate a quantum confinement structure consisting of a high-mobility
GaAs/AlGaAs heterojunction overgrown on top of an ex-situ cleaved substrate
corner. The resulting corner-junction quantum-well heterostructure effectively
bends a two-dimensional electron system (2DES) at an atomically sharp $90^{\rm
o}$ angle. The high-mobility 2DES demonstrates fractional quantum Hall effect
on both facets. Lossless edge-channel conduction over the corner confirms a
continuum of 2D electrons across the junction, consistent with
Schroedinger-Poisson calculations of the electron distribution. This growth
technique differs distinctly from cleaved-edge overgrowth and enables a
complementary class of new embedded quantum heterostructures.

17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th