Lighting up spintronics with re-writeable circuits

Researchers at the University of California Berkeley (UCB) and the City College of New York (CCNY) have developed a way of controlling the spin of a nucleus that could one day allow us to make rewritable spintronics circuits with light.

According to Professor Jeremy Reimer, UCB professor of chemical and biomolecular engineering and the study co-author, the major drawback of existing chips is their permanence: "Once the chip is printed, it can only be used one way," he said.

Once the chip design is etched into silicon, it is there forever. But the UCB and CCNY researchers had a different vision. "What you could have is a chip you can erase and rewrite on the fly with just the use of a light beam," said CCNY’s professor of Physics, Carlos Meriles.

The team discovered that they could encode information on an atomic nucleus by controlling its spin with a laser beam.

Historically, spintronics has concentrated on controlling the electron. But the spin state of an electron is inherently unstable, switching back and forth between states all the time. This makes it hard to control, and not very useful for storing information. So what the researchers did in this case was target the nucleus with laser light to create long-lived nuclear spin magnets that stabilise the spins of the electrons.

Shining a pattern of laser light onto a sample of gallium arsenide aligned all the spins of the nuclei – and therefore their electrons, simultaneously.

"If you can actually rewrite with a beam of light and alter this pattern, you can make the circuit morph to adapt to different requirements. Imagine what you can make a system like that do for you," Professor Meriles said.

The work is published here in the June 26th edition of the journal Nature Communications.