Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Low-temperature resistivity of single crystals YBa_2Cu_3O_{6+x} in the
  normal state   A scan of the superconductor -- nonsuperconductor transformation in single
crystals YBa_2Cu_3O_{6+x} (x about 0.37) was done in two alternative ways,
namely, by applying the magnetic field and by reducing the hole concentration
through the oxygen rearrangement. The in-plane normal-state resistivity
\rho_{ab} obtained in both cases was quite similar; its temperature dependence
can be fitted by logarithmic law in the temperature range of almost two
decades. However, a different representation of the \sigma_{ab}=1/\rho_{ab} by
a power law typical for a 3D-material near a metal -- insulator transition is
also plausible. The vertical conductivity \sigma_c=1/\rho_c followed the power
law and neither \sigma_c(T), nor \rho_c(T) could be fitted by log(T). It
follows from the \rho_c measurements that the transformation at T=0 is split
into two transitions: superconductor -- normal-metal and normal-metal --
insulator. In our samples, they are distanced in the oxygen content by \Delta
x\approx0.025.

25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg