Topology and Spin-Orbit Coupling in Low Dimensions Lead to Novel Directions in Spintronics
The appearance of new phenomena induced by spin-orbit coupling (SOC) and topology effects at surfaces, interfaces and low dimension materials has led to the emergence of novel directions in spintronics. I will describe examples of experimental results in some of these directions and the resulting perspectives for spintronic devices . - First example: The electron states at surfaces or interfaces of topological insulators, Rashba interfaces and some interfaces between oxides are characterized by a locking between the spin and momentum degrees of freedom. Thanks to the Edelstein and Inverse Edelstein Effects, this locking can be exploited for very efficient conversions between spin and charge currents (which, parenthetically, is the basic function in any spintronic device). Promising similar effects are obtained in 2D materials with large SOC as ultra-thin films of transition metal dichalcogenides and can be also expected in graphene/TMD heterostructures. - Second example, the chiral spin interactions (Dzyaloshinskii-Moriya interactions) induced by SOC at the interface of a magnetic film with a heavy metal can be used to create skyrmions, nanoscale spin whirls that are stabilized by their topology. The recent results in several groups on the electrical creation, manipulation and detection of skyrmions at room temperature in magnetic multilayers represent real advances on the route to applications.  Example of recent review: A. Soumyanarayanan, N. Reyren, A. Fert and C. Panagopoulos, Nature 539, 509 (2016).