Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Low temperature transport in granular metals   We investigate transport in a granular metallic system at large tunneling
conductance between the grains. We show that at low temperatures, $T\leq
g_T\delta $, where $\delta$ is the single mean energy level spacing in a grain,
the coherent electron motion at large distances dominates the physics, contrary
to the high temperature ($T > g_T \delta $) behavior where conductivity is
controlled by the scales of the order of the grain size. The conductivity of
one and two dimensional granular metals, in the low temperature regime, decays
with decreasing temperature in the same manner as that in homogeneous
disordered metals, indicating thus an insulating behavior. However, even in
this temperature regime the granular structure remains important and there is
an additional contribution to conductivity coming from short distances. Due to
this contribution the metal-insulator transition in three dimensions occurs at
the value of tunnel conductance $g_T^C=(1/6\pi)\ln (E_C/\delta)$, where $E_C$
is the charging energy of an isolated grain, and not at the generally expected
$g_T^C \propto 1$. Corrections to the density of states of granular metals due
to the electron-electron interaction are calculated. Our results compare
favorably with the logarithmic dependence of resistivity in the high-$T_c$
cuprate superconductors indicating that these materials may have a granular
structure.

13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph