Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution of a Metal to Insulator Transition in
  Ca$_{2-x}$Na$_{x}$CuO$_{2}$Cl$_{2}$, as seen by ARPES   We present angle resolved photoemission (ARPES) data on Na-doped
Ca$_2$CuO$_2$Cl$_2$. We demonstrate that the chemical potential shifts upon
doping the system across the insulator to metal transition. The resulting low
energy spectra reveal a gap structure which appears to deviate from the
canonical $d_{x2-y2} ~ |cos(k_x a)-cos(k_y a)|$ form. To reconcile the measured
gap structure with d-wave superconductivity one can understand the data in
terms of two gaps, a very small one contributing to the nodal region and a very
large one dominating the anti-nodal region. The latter is a result of the
electronic structure observed in the undoped antiferromagnetic insulator.
Furthermore, the low energy electronic structure of the metallic sample
contains a two component structure in the nodal direction, and a change in
velocity of the dispersion in the nodal direction at roughly 50 meV. We discuss
these results in connection with photoemission data on other cuprate systems.

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The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
9
The categories of this paper are: nlin