A new approach that uses light to switch the magnetic states of a material could lead to faster, smaller and more energy-efficient data storage.
Engineers at the University of California San Diego published their findings in Nature Communications .
In hard drives and other data storage technologies, tiny magnetic regions represent the 1s and 0s that make up digital information. Switching between those magnetic states typically requires an external magnetic field. But that approach uses a large amount of energy and limits how quickly information can be written.
UC San Diego engineers demonstrate a different approach that uses light instead of a magnet to switch magnetic information — a process called optical switching. Because light can deliver energy extremely quickly and can be precisely concentrated into a small area, it offers the potential to control magnetic bits more rapidly and efficiently. The researchers estimate that optical switching could be more than 1,000 times faster than approaches that rely on external magnetic fields.
Their approach uses an ultrafast laser beam that they uniquely shaped and engineered to be extremely small — about tens of orders of magnitude smaller than the beams used in previous approaches.
Being able to control magnetization in a material using this specially engineered light could potentially allow more data to be packed into a smaller area. “The smaller the size of the beam, the smaller and more dense the optical memory,” said study senior author Abdoulaye Ndao, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering.
Previous research had shown that optical switching was possible only in very thin magnetic stacks — that consisted of no more than three magnetic layers — and when a specific type of polarized light was used. “Past experiments had found that increasing the material’s thickness beyond three layers suppressed optical switching,” Ndao said. “That put a constraint on the overall thickness of the magnetic material and thus, its ability to retain memory in the long term.”
But by shaping and shrinking the light, Ndao’s team overcame both limitations. They demonstrated optical switching in a thicker magnetic material made of nine alternating layers of platinum and cobalt. They also found that they no longer needed to rely on the light’s polarization to achieve switching.
“We’ve optically engineered the light to change the physics that’s happening in the material at the micro- and nanoscale,” said study first author Muhammad Waleed Khalid, an electrical and computer engineering Ph.D. student in Ndao’s research group.
The key is concentrating the energy of the light beam onto a tiny area and exposing it to multiple ultrafast pulses. At this extremely small scale, the first pulses heat a tiny region enough to create a reversed magnetic area. Subsequent laser pulses gradually expand the switched region until it becomes stable.
“Working with a specialized laser allowed us to optically engineer the beam to have a certain shape and size,” Khalid said. “That gave us the room to explore more fundamental physics, which cannot be done with conventional beam lasers.”
The findings presented their own set of challenges. “The effects we were seeing were so new and unusual that we had a difficult time convincing others in the field that our discovery was not a one-time fluke. We spent a lot of time and effort repeating and verifying our experiments to substantiate our work to the optics community,” Khalid added.
This research project brought together expertise in optics and magnetic materials — two fields that do not typically overlap, Ndao noted. Ndao’s optics research group joined forces with Eric Fullerton, an expert in thin-film magnetic materials who is a professor of electrical and computer engineering, as well as chemical and nano engineering at UC San Diego, and the Endowed Chair Professor of UC San Diego’s Center for Memory and Recording Research. The collaboration allowed the researchers to approach a longstanding challenge in magnetic memory from the optical side.
“Instead of designing a new material to enable optical switching, we redesigned the light itself and showed new properties that were not previously thought to be possible,” Ndao said.
Several challenges remain before the technology could become part of commercial storage devices. The technology currently uses a specialized ultrafast laser that cannot yet be readily integrated into computer chips. Another potential path is to identify magnetic materials that can produce similar effects using lasers that are easier to incorporate into electronic systems.
The researchers are also working to shrink the laser beam further, potentially to a few hundred nanometers. They are investigating optical structures that could confine light into even smaller spaces. Their goal is to understand how specially engineered light can be used to control magnetism at increasingly small scales.
Full study: “ Optical beam shaping induced reconfigurable magnetic domains ”
The authors would like to acknowledge financial support from the 2023 Beckman Young Investigator Award; the Arnold and Mabel Beckman Foundation 2024 Alfred P. Sloan Research Fellowship; the Moore Foundation to the PAIR UP Imaging Science Program; and the Air Force Office of Scientific Research MURI (Award No. FA9550-22-1-0312). This research was supported by the National Science Foundation through the UC San Diego Materials Research Science and Engineering Center (MRSEC grant number DMR-2614051). This work was performed in part at the San Diego Nanotechnology Infrastructure (SDNI) at UC San Diego, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation (ECCS-2025752).
Nature Communications
Optical beam shaping induced reconfigurable magnetic domains
15-Sep-2026