A reshaped ultrafast laser beam let researchers switch magnetic information in a nine-layer material, according to a ScienceDaily report on work by engineers at the University of California San Diego (UC San Diego). The laboratory demonstration could point toward denser and faster memory, but it did not establish that a computer memory device is ready to build or that this experiment achieved a thousandfold speed increase. The research paper, “Optical beam shaping induced reconfigurable magnetic domains,” is listed in Nature Communications.
Many storage systems encode information as 1s and 0s in tiny magnetic regions. Changing those regions usually involves applying an external magnetic field, a process the report says uses considerable energy and limits how quickly information can be written. Optical switching offers a different approach: use light to change the magnetic state.
The team shaped and reduced the size of an ultrafast laser beam to concentrate its energy on a small area. With it, the researchers demonstrated switching in a magnetic structure made of nine alternating platinum and cobalt layers, without an external magnetic field. The report describes the beam as dramatically smaller than those used in earlier experiments, but gives no dimension for the beam in this demonstration.
The result addresses two constraints reported for earlier optical-switching experiments. Those experiments had worked only in very thin magnetic structures of up to three layers and required light with a particular polarization, or orientation of its electromagnetic waves. The new demonstration worked in a thicker structure and did not require a particular polarization. This matters because thicker magnetic structures can help preserve stored information over longer periods, according to the report.
The process uses a sequence of ultrafast pulses. The first pulses briefly heat a localized area and cause a small region to reverse its magnetic orientation. Further pulses enlarge that reversed region until the new magnetic state becomes stable. This sequence lets the researchers control the magnetic state by engineering the light’s shape and size.
The report says optical switching could potentially operate more than 1,000 times faster than conventional methods that rely on external magnetic fields. That is a projected capability, not a measured speed reported for this demonstration. Faster switching, along with the ability to focus light on smaller magnetic regions, could eventually support memory that writes more quickly and stores more information in a limited area. Those are prospective benefits, not results from a deployed memory device.
The work brought together optics and magnetic-materials expertise at UC San Diego. The report identifies Abdoulaye Ndao, a professor of electrical and computer engineering, as the study’s senior author, and Muhammad Waleed Khalid, an electrical and computer engineering doctoral student, as its first author. Ndao’s group worked with Eric Fullerton, a UC San Diego specialist in thin-film magnetic materials. The team focused on changing how light interacts with an existing material rather than designing a new material for optical switching. The researchers also repeated and checked their experiments because the results differed from what earlier work had suggested was possible.
A major engineering challenge remains: the specialized ultrafast laser used in the experiments is not easily incorporated into computer chips. The researchers are exploring magnetic materials that might respond to laser systems better suited to electronic hardware. They also aim to shrink the beam further, toward a few hundred nanometers, using optical structures to concentrate light into smaller regions. Whether those steps can yield practical memory hardware remains an open question.