Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Highly enhanced thermopower in two-dimensional electron systems at
  milliKelvin temperatures   We report experimental observation of an unexpectedly large thermopower in
mesoscopic two-dimensional (2D) electron systems on GaAs/AlGaAs
heterostructures at sub-Kelvin temperatures and zero magnetic field. Unlike
conventional non-magnetic high-mobility 2D systems, the thermopower in our
devices increases with decreasing temperature below 0.3 K, reaching values in
excess of 100 $\mu$V/K, thus exceeding the free electron estimate by more than
two orders of magnitude. With support from a parallel independent study of the
local density of states, we suggest such a phenomenon to be linked to intrinsic
localized states and many-body spin correlations in the system.

1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
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The categories of this paper are: nucl-ex
2
The categories of this paper are: math