Phys. Rev. B 91, 020403(R) (2015)

The basic building block for logic that uses the electron's spin rather than its charge is the spin analogue of the transistor: a device whose spin-flow between two terminals can be modulated. Although several methods have been developed to inject spins into non-magnetic materials, which would form the channels, techniques for manipulating spin currents are scarce. Estitxu Villamor and colleagues now show that magnetic gating can provide such manipulation.

In the original proposal for the spin transistor, spin control occurs by tuning the spin–orbit interaction with electric fields. Most materials that are good for spin transport, however, have spin–orbit interactions too small for this to be viable. By fabricating a lateral spin valve on top of a ferromagnetic insulator whose magnetization could be tuned with small magnetic fields, Estitxu Villamor et al. demonstrated a magnetically controlled modulation of the pure spin currents in a non-magnetic channel.

This magnetic gating arises from the interaction of the spins at the interface between the channel and the substrate, providing access to a far-reaching yet perplexing parameter of spintronics: the spin-mixing conductance.