Spin orbitronics – generation and manipulation of spin currents
An important new focus in the field of spintronics over the past several years has been that of spin-orbitronics in which the spin-orbit coupling leads to a number of new and exciting effects. Of particular interest is the conversion of charge currents to spin currents via the spin Hall effect. For many years it was believed that this effect in metals was very tiny but recently charge to spin conversion efficiencies of up to ~50% in conventional metals, and efficiencies of greater than 100% have been reported for topological insulators. The latter, however, remains controversial. Spin currents provide angular momentum: thus the spin currents can be detected via diffusing them into neighboring magnetic layers and detecting the response of the magnetic layer from the spin orbit torques that thereby act on the magnetic layer. Alternatively, the spin currents can be used to drive magnetic domain walls. Recently we have shown that nanosecond long current pulses can drive chiral domain walls at speeds of up to more than 1,000 m/sec in synthetic antiferromagnetic racetracks which have no net magnetization . This project concerns the study of the spin Hall effect in conventional and topological metals especially Weyl semi-metals. The proposed project will involve the preparation of Weyl semi-metals using pulsed laser deposition techniques and the study of the spin Hall effect in such layers. A second project could involve all-optical switching wherein femtosecond long intense optical pulses are used to switch the magnetization of novel magnetic layers.
Yang, S.-H.; Ryu, K.-S.; Parkin, S. S. / Nature Nanotechnology 10, 221-226 (2015)