Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sputtering induced re-emergence of the topological surface state in
  Bi$_2$Se$_3$   We study the fate of the surface states of Bi$_2$Se$_3$ under disorder with
strength larger than the bulk gap, caused by neon sputtering and nonmagnetic
adsorbates. We find that neon sputtering introduces strong but dilute defects,
which can be modeled by a unitary impurity distribution, whereas adsorbates,
such as water vapor or carbon monoxide, are best described by Gaussian
disorder. Remarkably, these two disorder types have a dramatically different
effect on the surface states. Our soft x-ray ARPES measurements combined with
numerical simulations show that unitary surface disorder pushes the Dirac state
to inward quintuplet layers, burying it below an insulating surface layer. As a
consequence, the surface spectral function becomes weaker, but retains its
quasiparticle peak. This is in contrast to Gaussian disorder, which smears out
the quasiparticle peak completely. At the surface of Bi$_2$Se$_3$, the effects
of Gaussian disorder can be reduced by removing surface adsorbates using neon
sputtering, which, however, introduces unitary scatterers. Since unitary
disorder has a weaker effect than Gaussian disorder, the ARPES signal of the
Dirac surface state becomes sharper upon sputtering.

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The categories of this paper are: hep-th
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph