Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Angular dependence of the penetration depth in unconventional
  superconductors   We examine the Meissner state nonlinear electrodynamic effects on the field
and angular dependence of the low temperature penetration depth, $\lambda$, of
superconductors in several kinds of unconventional pairing states, with nodes
or deep minima (``quasinodes'') in the energy gap. Our calculations are
prompted by the fact that, for typical unconventional superconducting material
parameters, the predicted size of these effects for $\lambda$ exceeds the
available experimental precision for this quantity by a much larger factor than
for others. We obtain expressions for the nonlinear component of the
penetration depth, $\Delta\lambda$, for different two- and three- dimensional
nodal or quasinodal structures. Each case has a characteristic signature as to
its dependence on the size and orientation of the applied magnetic field. This
shows that $\Delta\lambda$ measurements can be used to elucidate the nodal or
quasinodal structure of the energy gap. For nodal lines we find that
$\Delta\lambda$ is linear in the applied field, while the dependence is
quadratic for point nodes. For layered materials with
$\rm{YBa_2Cu_3O_{7-\delta}}$ (YBCO) type anisotropy, our results for the
angular dependence of $\Delta\lambda$ differ greatly from those for tetragonal
materials and are in agreement with experiment. For the two- and three-
dimensional quasinodal cases, $\Delta\lambda$ is no longer proportional to a
power of the field and the field and angular dependences are not separable,
with a suppression of the overall signal as the node is filled in.

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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
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The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
25
The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci