Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-Landau damping of magnetic excitations in systems with localized and
  itinerant electrons   We discuss the form of the damping of magnetic excitations in a metal near a
ferromagnetic instability. The paramagnon theory predicts that the damping term
should have the form $\Omega/\Gamma (q)$ with $\Gamma (q) \propto q$ (the
Landau damping). However, the experiments on uranium metallic compounds UGe$_2$
and UCoGe showed that $\Gamma (q)$ tends to a constant value at vanishing $q$.
A non-zero $\Gamma (0)$ is impossible in systems with one type of carriers
(either localized or itinerant) because it would violate the spin conservation.
It has been conjectured recently that a non-zero $\Gamma (q)$ in UGe$_2$ and
UCoGe may be due to the presence of both localized and itinerant electrons in
these materials, with ferromagnetism involving predominantly localized spins.
We present microscopic analysis of the damping of near-critical localized
excitations due to interaction with itinerant carriers. We show explicitly how
the presence of two types of electrons breaks the cancellation between the
contributions to $\Gamma (0)$ from self-energy and vertex correction insertions
into the spin polarization bubble and discuss the special role of the
Aslamazov-Larkin processes. We show that $\Gamma (0)$ increases with $T$ both
in the paramagnetic and ferromagnetic regions, but in-between it has a peak at
$T_c$. We compare our theory with the available experimental data.

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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
2
The categories of this paper are: math