Can we make electrons spin faster?

New insights into the movement of spins

Spins in polymers by no means only move with the electrons, but primarily via vibrations of the polymer chains

21.06.2019

When it comes to the speed of computers, conventional technologies are reaching their limits. New technologies are therefore required if computers are to become even faster in the future. Researchers at the Institute for Physics at Johannes Gutenberg University Mainz (JGU) have now made a discovery that lays a possible basis for such new technologies, such as the almost currentless computer.

The background: electrons rotate around their own axis, this is referred to as spin. It is used in hard drives, for example, to store information. The spin is therefore an absolutely essential requirement of today's electronics. Molecular electronics, in turn, is a further development of microelectronics, in which individual molecules form the components. For example, polymers can be used for this, i.e. long molecular chains. "Small changes in the structure of these polymers can be implemented very, very much more easily and precisely than corresponding changes in traditional semiconductor materials," explains Dr. Erik R. McNellis, group leader at the Institute for Physics at JGU. Because the polymers can be designed atom by atom. However, what was not yet clear: How do the spins move in these materials?

Spins jump between the polymer chains

"Until now, it was assumed that the spins move with the electrons - that is, they are coupled to the charge transport, i.e. the current," says McNellis. "We have now been able to refute this assumption: the spins by no means just move with the electrons, but rather hop from one polymer chain to the next as a result of vibrations. This opens up a whole new dimension in technology." These vibrations can be influenced by the design of the molecules, the device geometry, and the control of temperature. During the investigation, McNellis and his team performed the simulations for the experiments made at the University of Cambridge. The international research team has now published the results inNature Physics.

Faster, almost currentless computers

But what exactly is the new dimension that this discovery opens up? "On the one hand, we can use the spins to transmit information without using electricity. In this way, for example, energy-efficient, almost electricity-free computers can be produced," says McNellis, citing an application example. This is important, for example, for integrated circles that imitate the building blocks of the brain and are used for artificial intelligence. From another perspective, the use of molecular components in solid-state technology often offers unique advantages, such as organic light-emitting diodes (OLEDs) in screens. This goal is getting closer with this publication.

In a previous publication, the JGU researchers were able to show that the spins in a polymer move much farther than in traditional semiconductors - and that with far less manufacturing effort and higher design potential.