Breakthrough in 'spintronics' could lead to energy efficient chips

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.

Digital by nature

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.

Only a few atomic layers thick

To achieve an efficient information exchange, the researchers insert an ultra thin -- less than one nanometer thick -- layer of aluminum 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 magnetization in the semiconductor, with a controllable magnitude and orientation.

Importantly, 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 nanometers. 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 Organization for Scientific Research (NWO).