Dr Matteo Franchin and Prof Hans Fangohr

Electrons possess a property which makes them behave as small magnets: the spin. A flow of electrons is an electric current (flow of electric charge) and also a spin current. Spin currents do already have important applications in modern technology: they are used in magnetic sensors.

It is thanks to spin currents that amazing amounts of data can be stored in small space. Recent research has shown that not only spin currents can be used to efficiently read magnetic information, but they also can be used to write it. One example is given in the lenticular image, which shows the results of a computer simulation of a tiny magnetic wire (diameter of 20 nanometres, about 5000 times smaller than the diameter of a human air) made of a nickel iron alloy. An electric (and thus spin) current is able to produce a dynamical change in the magnetic state of the ferromagnetic cylinder. The arrows (density of magnetic moment) compress towards the right and - at the same time - rotate around the wire axis. This dynamical response is accompanied by the emission of microwaves. This system may then be used as a nano-sized microwave generator, which could allow improving existing data storage technologies or - in a quite futuristic scenario - could allow intra-chip or chip-to-chip wireless communication.