Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct Measurement of the Out-of-Plane Spin Texture in the Dirac Cone
  Surface State of a Topological Insulator   We have performed spin- and angle-resolved photoemission spectroscopy of
Bi2Te3 and present the first direct evidence for the existence of the
out-of-plane spin component on the surface state of a topological insulator. We
found that the magnitude of the out-of-plane spin polarization on a hexagonally
deformed Fermi surface (FS) of Bi2Te3 reaches maximally 25% of the in-plane
counterpart while such a sizable out-of-plane spin component does not exist in
the more circular FS of TlBiSe2, indicating that the hexagonal deformation of
the FS is responsible for the deviation from the ideal helical spin texture.
The observed out-of-plane polarization is much smaller than that expected from
existing theory, suggesting that an additional ingredient is necessary for
correctly understanding the surface spin polarization in Bi2Te3.

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The categories of this paper are: math
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex