Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optically-patterned nuclear doughnuts in GaAs/MnAs heterostructures   We demonstrate a scheme for optically patterning nuclear spin polarization in
semiconductor/ferromagnet heterostructures. A scanning time-resolved Kerr
rotation microscope is used to image the nuclear spin polarization that results
when GaAs/MnAs epilayers are illuminated with a focused laser having a Gaussian
profile. Rather than tracking the intensity profile of the laser spot, these
images reveal that the nuclear polarization forms an annular lateral structure
having circular symmetry with a dip rather than a peak at its center.

25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics