Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectroscopic signature of two superconducting gaps and their unusual
  field dependence in RuB$_2$   Recently RuB$_2$ was shown to be a possible two-gap, type-I superconductor.
Temperature dependent heat capacity measurements revealed a two-gap
superconducting ground state while magnetic field dependent magnetization
measurements indicated surprising type-I superconductivity with a very low
experimental critical field ($H_c$) $\sim$ 120 Oe. In this paper, we report
direct spectroscopic evidence of two superconducting energy gaps in RuB$_2$. We
have measured scanning tunnelling spectra exhibiting signature of two gaps on
different grains of polycrystalline RuB$_2$, possibly originating from multiple
bands. Analysis of the temperature dependent tunnelling spectra revealed that
the gaps from different bands evolve differently with temperature before
disappearing simultaneously at a single $T_c$. Interestingly, our experiments
also reveal that the gaps in quasiparticle density of states survive up to
magnetic fields much higher than the bulk $H_c$ and they evolve smoothly with
field, unlike what is expected for a type-I superconductor, indicating the
existence of a ``mixed state".

27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg