Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interlayer tunneling spectroscopy of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$:
  a look from inside on the doping phase diagram of high $T_c$ superconductors   A systematic, doping dependent interlayer tunneling spectroscopy of Bi2212
high $T_c$ superconductor is presented. An improved resolution made it possible
to simultaneously trace the superconducting gap (SG) and the normal state
pseudo-gap (PG) in a close vicinity of $T_c$ and to analyze closing of the PG
at $T^*$. The obtained doping phase diagram exhibits a critical doping point
for appearance of the PG and a characteristic crossing of the SG and the PG
close to the optimal doping. This points towards coexistence of two different
and competing order parameters in Bi2212. Experimental data indicate that the
SG can form a combined (large) gap with the PG at $T<T_c$ and that the
interlayer tunneling becomes progressively incoherent with decreasing doping.

17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph