Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconductivity of Cobalt in Thin Films   Due to competing long range ferromagnetic order, the transition metals Fe, Co
and Ni are not superconductors at ambient pressure. While superconductivity was
observed in a non-magnetic phase of Fe, stabilized under pressure, it is yet to
be discovered in Co and Ni under any experimental conditions. Here, we report
emergence of superconductivity in the recently discovered high-density
nonmagnetic face centered cubic phase in Co thin films below a transition
temperature (Tc) of ~5.4 K, as revealed in experiments based on point-contact
spectroscopy and resistance, and four-probe measurements of resistance at
ambient pressure. We confirm the non-magnetic nature of the dense fcc phase of
Co within first-principles density functional theory, and show that its
superconductivity below 5 K originates from anomalous softening of
zone-boundary phonons and their enhanced coupling with electrons upon biaxial
strain.

35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an