Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Surface-Barrier Effects in the Microwave Second-Harmonic Response of
  Superconductors in the Mixed State   We report on transient effects in the microwave second-order response of
different type of superconductors in the mixed state. The samples have
contemporarily been exposed to a dc magnetic field, varying with a constant
rate of 60 Oe/s, and a pulsed microwave magnetic field. The time evolution of
the signal radiated at the second-harmonic frequency of the driving field has
been measured for about 500 s from the instant in which the dc-field sweep has
been stopped, with sampling time of about 0.3 s. We show that the
second-harmonic signal exhibits two relaxation regimes; an initial exponential
decay, which endures roughly 10 s, and a logarithmic decay in the time scale of
minutes. Evidence is given that the decay in the time scale of minutes is ruled
by magnetic relaxation over the surface barrier.

7
The categories of this paper are: hep-th
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas