“Cool” spintronics to combat the power meltdown

Electronic devices are insatiable power guzzlers, which is why hitherto neglected semiconductor properties should be used to drastically reduce energy consumption in the future.

Up to twelve percent of global electricity already flows today into digital devices, according to the Intergovernmental Panel on Climate Change (IPCC). The culprits are data centers and networks, as well as smartphones, personal computers, notebooks, and tablets. And the trend is rising sharply.

That’s because the installed chips need increasingly higher power densities, heat up more, and hence consume more energy. After all, almost all the electrical energy that flows into an electronic device is ultimately converted into heat.

The right “spin” for data processing

Scientists worldwide are therefore researching more efficient solutions. One candidate is spintronics. In addition to the charge, it uses the spin of the electrons for data processing. This quantum mechanical property, which cannot actually be observed, “transforms” the electrons into tiny bar magnets that spin around their own axis. Both orientations, spin “up” or “down,” correspond to the binary states 0 and 1. Since this type of information processing does not involve any electrons that could collide with that atoms of the conductor, fewer heat losses occur.

The first commercial spintronics applications are magnetic field sensors in the read/write heads of modern computer hard disks, and non-volatile magnetic random access memories (MRAM), mainly for industrial use.

100 times less energy consumption thanks to spin waves

If, on the other hand, electron spins are used for data transmission and processing, then spin waves instead of the individual spins with their quantum particles (magnons) serve as information carriers. With regard to distribution and overlapping, they demonstrate similar properties to light or water waves.

New insights in spin research promise that the spin wave technology in microchips is able to significantly reduce the energy and space consumption of electronic devices.

On that basis, researchers at the Fraunhofer IZM, together with European partners, were able to connect “magnonic” components to a conventional computer and hence integrate them into standard in semiconductor systems. CMOS circuits ensure the compatibility since they are used in all standard computers, and save and process both digital and analog data.

In the project the group at Fraunhofer IZM designed a chip structure for frequencies of up to around 16 Gigahertz with almost identical wiring lengths for more than 100 channels. It acts as an interface between a conventional PC and a spinwave circuit made from sapphire or gardolinium gallium garnet (GGG).

Currently, only one logic gate runs on these spinwave chips. However, to implement more complex calculations, there should be space on them in the future for more than 100 gates. Accessing multiple high-frequency channels is also aimed at applications in high-frequency and communication systems, such as collision avoidance in autonomous driving.

With regard to data processing, spintronics is in its infancy. Research is still dealing mainly with the basics, although initial practical successes give hope. In any case, many experts agree that the new energy saving technology will succeed the current microelectronics.