Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiple Superconducting Transitions in {\alpha}-Sn Films Grown by
  Molecular Beam Epitaxy   Gray tin, also known as {\alpha}-Sn, has been attracting research interest
recent years due to its topological nontrivial properties predicted
theoretically. The Dirac linear band dispersion has been proved experimentally
by angle resolved photoemission spectroscopy. We have grown a series of
{\alpha}-Sn thin film samples in two types with different substrates and
thicknesses by molecular beam epitaxy. To explore the possible exotic physical
properties related to the topological band structures, we have measured the
electrical transport properties of our {\alpha}-Sn thin film samples and
observed multiple superconducting transitions. We have identified the
transitions above 4.5 K, besides the transition maybe related to the \b{eta}
phase around 3.7 K. The changes of the superconducting properties over time
reflect the aging effects in our samples. We have also confirmed the strain
effects on the superconducting transitions through altering the relative
thickness of our samples.

27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
1
The categories of this paper are: cs
18
The categories of this paper are: econ