Breakthrough in 'spintronics' could lead to energy efficient chips

Scientists from the MESA+ Institute for Nanotechnology of the University of Twente and the FOM Foundation have succeeded in transferring magnetic information directly into a semiconductor. For the first time, this is achieved at room temperature. This breakthrough brings the development of a more energy efficient form of electronics, so-called 'spintronics' within reach. The results are published on 26 November in Nature.

So far, information exchange between a magnetic material and a semiconductor was only possible at very low temperature. The successful demonstration of information exchange at room temperature is a pivotal step in the development of an alternative paradigm for electronics. The main advantage of this new 'spintronics' technology is the reduced power consumption: in present-day computer chips, excessive heat production is already a problem, and this will soon become a limiting factor.

Unlike conventional electronics that employs the charge of the electron and its transport, spintronics exploits another important property of the electron, namely the 'spin.' The sense of rotation of an electron is represented by a spin that either points up or down. In magnetic materials, the spin orientation can be used to store a bit of information as a '1' or a '0.' The challenge is to transfer this spin information to a semiconductor, such that the information can be processed in new spin-based electronic components. These are expected to operate at lower power consumption, since computations such as reversing the electron spin, require less power than the usual transport of charge.

To achieve an efficient information exchange, the researchers insert an ultra thin - less than one nanometre thick - layer of aluminium oxide between the magnetic material and the semiconductor: this corresponds to only a few atomic layers. The thickness and quality of this layer are crucial. The information is transferred by applying an electric current across the oxide interface, thereby introducing a magnetisation in the semiconductor, with a controllable magnitude and orientation. A very important aspect is that the method works for silicon: the prevalent electronic material for which highly advanced fabrication technology is available. The researchers found that the spin information can propagate into the silicon to a depth of several hundred nanometres. This is sufficient for the operation of nanoscale spintronic components, according to researcher Ron Jansen. Now the next step is: to built new electronic components and circuits and use these to manipulate spin information.

The spintronics research is performed by a team of researchers led by Ron Jansen at the MESA+ Institute for Nanotechnology, and is made possible by financial support from the Foundation FOM and a VIDI-grant received from the Netherlands Organisation for Scientific Research (NWO).