Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of Bound Surface States in Grain Boundary Junctions of High
  Temperature Superconductors   We have performed a detailed study of the tunneling spectra of bicrystal
grain boundary junctions (GBJs) fabricated from the HTS YBCO, BSCCO, LSCO, and
NCCO. In all experiments the tunneling direction was along the CuO planes. With
the exception of NCCO, for all materials a pronounced zero bias conductance
peak was observed which decreases with increasing temperature and disappears at
the critical temperature. These results can be explained by the presence of a
dominating d-wave symmetry of the order parameter resulting in the formation of
zero energy Andreev bound states at surfaces and interfaces of HTS. The absence
of a ZBCP for NCCO is consistent with a dominating s-wave symmetry of the pair
potential in this material. The observed nonlinear shift of spectral weight to
finite energies by applying a magnetic field is in qualitative agreement with
recent theoretical predictions.

24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg