Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theory of the Spin Seebeck Effect at a
  Topological-Insulator/Ferromagnetic-Insulator Interface   The spin-Seebeck effect refers to voltage signals induced in metals by
thermally driven spin currents in adjacent magnetic systems. We present a
theory of the spin-Seebeck signal in the case where the conductor that supports
the voltage signal is the topologically protected two-dimensional surface-state
system at the interface between a ferromagnetic insulator (FI) and a
topological insulator (TI). Our theory uses a Dirac model for the TI
surface-states and assumes Heisenberg exchange coupling between the TI
quasiparticles and the FI magnetization. The spin-Seebeck voltage is induced by
the TI surface states scattering off the nonequilibrium magnon population at
the surface of the semi-infinite thermally driven FI. Our theory is readily
generalized to spin-Seebeck voltages in any two-dimensional conductor that is
exchange-coupled to the surface of a FI. Surface-state
carrier-density-dependent signal strengths calculated using Bi$_2$Te$_3$ and
yttrium iron garnet material parameters are consistent with recent experiments.

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The categories of this paper are: funct-an
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: econ
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: astro-ph
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The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: eess
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The categories of this paper are: q-bio
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The categories of this paper are: gr-qc
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The categories of this paper are: cs