Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Microwave emission from a crystal of molecular magnets -- The role of a
  resonant cavity   We discuss the effects caused by a resonant cavity around a sample of a
magnetic molecular crystal (such as Mn${}_{12}$-Ac), when a time dependent
external magnetic field is applied parallel to the easy axis of the crystal. We
show that the back action of the cavity field on the sample significantly
increases the possibility of microwave emission. This radiation process can be
supperradiance or a maser-like effect, depending on the strength of the
dephasing. Our model provides further insight to the theoretical understanding
of the bursts of electromagnetic radiation observed in recent experiments
accompanying the resonant quantum tunneling of magnetization. The experimental
findings up to now can all be explained as being a maser effect rather than
superradiance. The results of our theory scale similarly to the experimental
findings, i.e., with increasing sweep rate of the external magnetic field, the
emission peaks are shifted towards higher field values.

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The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
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The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
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The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph