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 November 26 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.
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. 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 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).
Posted November 26th, 2009
