Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modelling Electron Spin Accumulation in a Metallic Nanoparticle   A model describing spin-polarized current via discrete energy levels of a
metallic nanoparticle, which has strongly asymmetric tunnel contacts to two
ferromagnetic leads, is presented.
  In absence of spin-relaxation, the model leads to a spin-accumulation in the
nanoparticle, a difference ($\Delta\mu$) between the chemical potentials of
spin-up and spin-down electrons, proportional to the current and the Julliere's
tunnel magnetoresistance. Taking into account an energy dependent
spin-relaxation rate $\Omega (\omega)$, $\Delta\mu$ as a function of bias
voltage ($V$) exhibits a crossover from linear to a much weaker dependence,
when $|e|\Omega (\Delta\mu)$ equals the spin-polarized current through the
nanoparticle. Assuming that the spin-relaxation takes place via electron-phonon
emission and Elliot-Yafet mechanism, the model leads to a crossover from linear
to $V^{1/5}$ dependence. The crossover explains recent measurements of the
saturation of the spin-polarized current with $V$ in Aluminum nanoparticles,
and leads to the spin-relaxation rate of $\approx 1.6 MHz$ in an Aluminum
nanoparticle of diameter $6nm$, for a transition with an energy difference of
one level spacing.

7
The categories of this paper are: hep-th
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
0
The categories of this paper are: hep-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
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat