Spin orbit coupling induced phenomena in spintronic devices
Date
2017
Authors
Journal Title
Journal ISSN
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Publisher
University of Delaware
Abstract
Spin-orbit coupling (SOC) is a relativistic interaction between spin and orbital momentum that induces a plenty of novel phenomena including spin Hall effect (SHE), Rashba-Edelstein effect (REE), topological surface states (TSS), spin orbit toques (SOTs), etc. In this thesis work, we have conducted relevant researches in order to develop materials and heterostructures, as well as new phenomena that can lead to high efficiency in generating SOTs or switching the magnetization. We have also investigated fabrication technique that speeds up the fabrication of nanoscale devices. ☐ A nanofabrication procedure has been developed based on shadow mask and angle deposition techniques. It is an efficient bottom-up, as oppose to top-down lithography technique, to fabricate rather complicate devices. A comprehensive study of shadow mask technique has been accomplished to fabricate magnetoelectric (ME) device based on voltage controlled boundary magnetism of antiferromagnet Cr2O3 and magnetic tunnel junctions. ☐ The researches on SOTs focus on SHE, REE and TSS in which a charge current is converted into spin current that exerts the SOTs on the magnetization of neighboring ferromagnetic layer. First, we have studied the charge to spin conversion efficiency in 3d light transition metal vanadium in V/CoFeB bilayer, which shows a surprisingly large spin Hall angle that is comparable to that of Pt. Second, we have investigated the temperature dependent SOTs in Bi2Se3/Co and Bi2Se3/Ni80Fe20 bilayers, and confirmed the existence of TSS in Bi2Se3/Co systems. Finally, we have discovered a novel spin rotation behaviors in a ferromagnetic metal, where the spin polarization is rotated around the magnetization. It implies that a perpendicularly polarized spin current can be generated by an in-plane charge current through a ferromagnetic metal, which can be applied to realize the anti-damping switching process in magnetic heterostructures.
Description
Keywords
Pure sciences, Coupling, Orbit, Spin, Spintronic