Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Robustness of the Berezinskii-Kosterlitz-Thouless Transition in
  Ultrathin NbN Films near the Superconductor-Insulator Transition   Occurrence of the Berezinskii-Kosterlitz-Thouless (BKT) transition is
investigated by superfluid density measurements for two-dimensional (2D)
disordered NbN films with disorder level very close to a
superconductor-insulator transition (SIT). Our data show a robust BKT
transition even near this 2D disorder-tuned quantum critical point (QCP). This
observation is in direct contrast with previous data on deeply underdoped
quasi-2D cuprates near the SIT. As our NbN films approach the QCP, the
vortex-core energy, an important energy scale in the BKT transition, scales
with the superconducting gap, not with the superfluid density, as expected
within the standard 2D-XY model description of BKT physics.

15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex