Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Competing quantum Hall phases in the second Landau level in low density
  limit   We present in this Letter the results from two high quality, low density GaAs
quantum wells. In sample A of electron density n=5.0x10^10 cm^-2, anisotropic
electronic transport behavior was observed at \nu=7/2 in the second Landau
level. We believe that the anisotropy is due to the large Landau level mixing
effect in this sample. In sample B of density 4.1x10^10 cm^-2, strong 8/3, 5/2,
and 7/3 fractional quantum Hall states were observed. Furthermore, our energy
gap data suggest that, similar to the 8/3 state, the 5/2 state may also be spin
unpolarized in the low density limit. The results from both samples show that
the strong electron-electron interactions and a large Landau level mixing
effect play an import role in the competing ground states in the second landau
level.

28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat