Figure: Injection principle of a pure spin current of spin up (blue) and spin down (red) oncoming giving rise to the production of a charge current at the interface between the silver (Ag) and Bismuth (Bi).
Spintronics, or spin electronics, is based on the use of ferromagnetic materials to generate and manipulate information based on electron spin rather than its charge. In this work, we show that it is also possible to use the Rashba effect present at the interface between two non- magnetic materials.
Spintronics aims to capitalize on the spin state of electrons rather than their charge to carry and manipulate information. Indeed, the electron (or hole) carries a charge but also a spin, which is a further degree to convey information and to allow its manipulation. The approach conventionally used is to pass an electric current through a ferromagnetic material; the electric current will then be spin-polarized, which means that a non-zero spin current will be produced, in addition to the charge current. The ability to generate and detect spin current is critical. Indeed, the way the spins will be able to flow into a structure will depend on the state of magnetization, and reciprocally a sufficiently large flow of spin will control the magnetization state. Many innovative applications using these phenomena are already appearing especially in the field of sensors, memories and microwave transmitters.
In our work we used a system of thin layers of Bismuth and Silver. At the surface of Bismuth, especially at the interface with Silver, a strong Rashba effect develops. The electric field at the interface between these two materials will then act on the spin of the carrier in the manner of a magnetic field and produce a spin flow, in parallel with a charge current. We injected a spin current on this interface and were able to demonstrate that this spin current was converted in a charge current. This basic mechanism may be particularly useful to produce and detect spin currents but also for heat recovery, using materials of low conductivity in order to produce high power.
This work was done in collaboration between teams from INAC (Institut Nanosciences et Cryogénie in Grenoble), the CNRS/Thales physics team in Palaiseau and the University of Zaragoza in Spain.
Spin to charge conversion using Rashba coupling at the interface between non-magnetic materials. J. C. Rojas Sanchez, L. Vila, G. Desfonds, S. Gambarelli, J.P. Attané, J. M. De Teresa, C. Magén, A. Fert. Nat. Commun. 4:2944
doi: 10.1038/ncomms3944 (2013)
Last update : 04/18 2014 (1019)