Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spatial gradient of dynamic nuclear spin polarization induced by
  breakdown of quantum Hall effect   We studied spatial distribution of dynamic nuclear polarization (DNP) in a
Hall-bar device in a breakdown regime of the quantum Hall effect (QHE). We
detected nuclear magnetic resonance (NMR) signals from the polarized nuclear
spins by measuring the Hall voltage $V_{xy}$ using three pairs of voltage
probes attached to the conducting channel of the Hall bar. We find that the
amplitude of the NMR signal depends on the position of the Hall voltage probes
and that the largest NMR signal is obtained from the pair of probes farthest
from the electron-injecting electrode. Combined with results on pump-and-probe
measurements, we conclude that the DNP induced by QHE breakdown develops along
the electron-drift direction.

34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol