Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Negative differential conductance and magnetoresistance oscillations due
  to spin accumulation in ferromagnetic double-island devices   Spin-dependent electronic transport in magnetic double-island devices is
considered theoretically in the sequential tunneling regime. Electric current
and tunnel magnetoresistance are analyzed as a function of the bias voltage and
spin relaxation time in the islands. It is shown that the interplay of spin
accumulation on the islands and charging effects leads to periodic modification
of the differential conductance and tunnel magnetoresistance. For a
sufficiently long spin relaxation time, the modulations are associated with
periodic oscillations of the sign of both the tunnel magnetoresistance and
differential conductance.

7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci