ABSTRACT
Spintronics is an emerging field in which the quantum mechanical
spin of the electron is used for switching purposes and to communicate information [1]. Spin-dependent effects arise from
interactions of the electron with an external magnetic field or with
magnetic properties of the conduction material. Future spintronic
devices hold the promise of faster switching speeds, less electric
power consumption, and higher density of circuit elements [2].
Aharonov-Bohm (AB) rings are examples of nanoscale devices
which have shown the potential for spin-dependent transport
[3, 4]. An important feature of an AB interferometer with a
quantum dot (QD) embedded in one or both arms is the ability
to probe the total spin of the electronic state of the QD. When
electron spin-degeneracy is lifted, the transmission resonant modes
through the QDs indicate powerful methods for producing spin-
polarization filters which have important potential applications in
spintronic device technologies. Investigating electron-spin transport
in semiconductor nanostructures and nanoscale electronic devices
including QDs has attracted much attention [5-8]. QDs with spin-
split energy levels embedded in AB rings offer unique possibilities
for manipulating and utilizing the spin of electrons in individual
quantum states [9]. The main topics of research have focused on
studying the fundamental aspects of the spin-dependent transport
(e.g., spin coherence times, many-body effects such as the Kondo
effect or spin-charge separation [10, 11], and spin-dependent
tunneling [12]) and to developing and optimizing semiconductor
spintronics device applications, such as spin transistors and spin
qubits [5]. More recently, both experimental and theoretical studies
have shown the possibility of preparing and manipulating spin-
polarized electron states in graphene [13, 14].