Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of Fermi-energy dependent unitary impurity resonances in a
  strong topological insulator Bi2Se3 with scanning tunneling spectroscopy   Scanning tunneling spectroscopic studies of Bi2Se3 epitaxial films on Si
(111) substrates reveal highly localized unitary impurity resonances associated
with non-magnetic quantum impurities. The strength of the resonances depends on
the energy difference between the Fermi level ({E_F}) and the Dirac point
({E_D}) and diverges as {E_F} approaches {E_D}. The Dirac-cone surface state of
the host recovers within ~ 2{\AA} spatial distance from impurities, suggesting
robust topological protection of the surface state of topological insulators
against high-density impurities that preserve time reversal symmetry.

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The categories of this paper are: eess
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org