Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electrically controlled quantum dot based spin current injector   We present a proposal for a fully electrically controllable quantum dot based
spin current injector. The device consists of a quantum dot that is strongly
coupled to a ferromagnetic electrode on one side and weakly coupled to a
nonmagnetic electrode on the other side. The presence of ferromagnetic
electrode results in an exchange field that splits the dot level. We show that
this exchange-induced splitting can lead to almost full spin polarization of
the current flowing through the device. Moreover, we also demonstrate that the
sign of the polarization can be changed by the gate or the bias voltage within
a switching time in the nanosecond range. Thus the proposed device can operate
as an electrically controlled, fast switchable spin current source, which can
be realized in various state-of-the-art nanostructures.

28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg