University of California San Diego engineers have demonstrated that using specially engineered light to switch magnetic states could make data storage more than 1,000 times faster than current approaches relying on external magnetic fields. Published in Nature Communications, the finding details a process called optical switching that bypasses traditional energy limitations in hard drives and digital memory devices.
How Optical Switching Overcomes Thickness Limits
Traditional data storage relies on tiny magnetic regions representing 1s and 0s, which require external magnetic fields to switch states. That method uses high amounts of energy and restricts writing speeds. UC San Diego researchers utilized an ultrafast laser beam, shaped and shrunk to be tens of orders of magnitude smaller than conventional beams, to control magnetization.
Previous experiments limited optical switching to very thin magnetic stacks containing no more than three layers, as adding thickness suppressed the switching effect. Study senior author Abdoulaye Ndao, a professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering, noted that past constraints hindered long-term memory retention. By engineering the light beam’s shape and size, Ndao’s team successfully demonstrated optical switching in a nine-layer material made of alternating platinum and cobalt layers without relying on light polarization.
“The smaller the size of the beam, the smaller and more dense the optical memory,” Ndao said.
Engineering Light at the Microscale
The technique concentrates light beam energy onto a tiny area using multiple ultrafast pulses. Initial pulses heat a microscale region to create a reversed magnetic area, while subsequent pulses expand the switched region until stable. Muhammad Waleed Khalid, an electrical and computer engineering Ph.D. student and study first author, explained that the specialized laser allowed the team to explore fundamental physics unattainable with standard lasers.
The collaboration combined optics research with thin-film magnetic materials expertise. Ndao partnered with Eric Fullerton, professor of electrical and computer engineering, chemical and nano engineering, and Endowed Chair Professor of UC San Diego’s Center for Memory and Recording Research. Instead of designing a new material, the team redesigned the light itself to unlock properties previously thought impossible.
Pathways to Commercialization
Commercial integration presents ongoing hurdles. The current setup utilizes a specialized ultrafast laser that cannot yet integrate directly onto computer chips. Researchers are currently investigating alternative magnetic materials compatible with accessible lasers and working to shrink laser beams down to a few hundred nanometers using specialized optical structures.