الفهرس 
Theoretical FormulationOnly 14 pages are availabe for public view
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Abstract
The Spin-based electronic devices have many advantages including
longer coherent lifetime and faster data processing speed. Thus the
generation, manipulation and detection of spin currents has the subject of
intense research recently. The present thesis is devoted to investigate the
spin-transport characteristics of two different mesoscopic spintronic
devices which are: spin-interference mesoscopic device and mesoscopic
superconductor-ferromagnetic hybrid device.
For the first device, the spin-dependent conductance of such device
is investigated. This device is in the form of ring, in which a quantum dot
is embedded in one arm. This quantum dot is connected to one lead via
tunnel barrier. Both Aharonov-Casher and Aharonov-Bohm effects are
studied. That is, the spin polarized conductance is mainly induced by a
combined effect of Rashba spin-orbit interaction and a magnetic flux.
Also, quantum size effect for this device is investigated. The present
results confirm the interplay of spin-orbit coupling and quantum
interference effects in such confined quantum systems. This investigation
is valuable for spintronics application, for example, quantum information
processing Now, concerning the second device, the spin polarization and the
corresponding tunneling magnetoresistance (TMR) for such junction are
calculated. The results show that these parameters are strongly depends
on the exchange field energy and the bias voltage. The dependence of the
polarization of the angle of precession is due to the spin flip through
tunneling process. The present results could be interpreted as due to spin
imbalance of carriers resulting in suppression of gap energy of the
superconductor. The present investigation is valuable for manufacturing
magnetic recording devices and nonvolatile memories which imply a very
high spin coherent transport for such junction.
Keywords: Aharonov-Casher effect- Aharonov-Bohm effect - Quantum
Dot - Ferromagnetic-superconductor double junctions.