University of Minnesota
School of Physics & Astronomy


C-SPIN materials may comprise future computers

Paul Crowell
Paul Crowell
Richard Anderson

The end is near for CMOS technology, and Paul Crowell is trying to do something about that. “CMOS” stands for “complementary metal-oxide-semiconductor,” and CMOS technology is responsible for all the calculators, laptops, cell phones, tablets, and just about every non-abacus computing device in the world. Over the past 70 years or so, scientists and engineers have consistently made CMOS transistors smaller and more energy efficient, which is why your cell phone has more computing power than the most powerful mainframe in 1960.

But the smaller transistors get, the more they leak electric current, which makes them less energy efficient and more difficult to keep from overheating. Experts predict that there will be no more room for improvement – literally – sometime around 2020.

So what’s next?

Paul Crowell is part of a nationwide effort to answer that question. As the co-Director of the Center for Spintronic Materials, Interfaces, and Novel Devices (C-SPIN), currently housed in Keller Hall, he is guiding an effort to replace the CMOS transistor with one based on an electron’s spin. To put it another way, the scientists in C-SPIN are trying to figure out how to make a computer whose binary information is not coded by means of electric current, but the spin direction of electrons in super-small magnets. If they succeed, they will push the absolute limits of transistor size down the road and develop computers that operate on a fraction of the energy today’s computers require.

It’s a tall order, which is why C-SPIN involves 32 professors and over 100 graduate students and postdoctoral researchers from 18 universities around the country. Funded by the Center, these experts in particle physics, nanotechnology, computer architectures, device design, materials science, and other disciplines are collaborating to tackle the many unknowns associated with spin-based technology.
Crowell’s research for C-SPIN is based primarily on groundbreaking work he did before the Center opened in January 2013. Crowell developed methods for testing the various “spin properties” of materials – that is, how well their electrons can switch spin direction and how easily they pass spin direction to other electrons. The better the spin properties, the lower the energy needed to process and store information. C-SPIN scientists from around the country send Crowell materials for testing, and Crowell sends his results to theoreticians who try to figure out the relationship between the material and its spin properties. These results get sent back to fabricators, who try to make “new and improved” spin materials.

Crowell’s C-SPIN research has, like much basic science, led to a number of surprises. Many materials with good spin properties become useless when connected to others, and some materials have had much better spin properties than predicted. As the collaborative process is becoming more efficient, Crowell hopes that he and his fellow scientists can identify the best spin materials and begin fabricating and testing spin-based devices sometime in 2015.
Crowell is also responsible for writing quarterly research reports for the Center’s sponsors, enabling him to see possibilities for pooling resources and specialties and to initiate several new collaborative research projects.

Crowell thinks it likely that the computers of the future will have components based on several technologies that currently do not exist, including spin-based technologies. He also emphasizes that spin-based technologies can be used in sensors, magnetic data storage disks, and many other electronic devices that can turn spin properties into useful information. So while the end of CMOS may be near, the beginning of a spin-based electronic future may be just beginning.