Data Storage · Photonics & Magnetism
For years, better magnetic memory meant hunting for better magnetic materials. A San Diego team just tried the opposite: leave the material alone and redesign the light.
By reshaping a laser beam, they switched nine layers of platinum and cobalt, three times the limit of earlier experiments.
Engineers at the University of California San Diego reshaped and shrank an ultrafast laser beam to switch a stack of nine alternating platinum and cobalt layers with light, extending optical switching beyond the three-layer limit seen in earlier experiments. The new approach also worked without requiring a specific polarization of light. Switching builds over multiple laser pulses: early pulses reverse a tiny region with concentrated heat, and later pulses expand it until it is stable. Optical switching could be more than 1,000 times faster than magnetic-field methods, according to the researchers' estimate, though this study demonstrates the switching rather than a finished device. The specialized laser cannot yet be integrated into computer chips, so practical use will require smaller beams and more chip-friendly lasers. Published in Nature Communications.
An engineered laser beam, not a new material, is what let UC San Diego switch a nine-layer magnetic stack with light.
Signal Depth Navigator
UC San Diego engineers reshaped a laser beam to switch a nine-layer magnetic stack with light, instead of redesigning the material. This article covers how magnetic memory stores and writes data, why optical switching could be so much faster, how the three-layer barrier was broken, how pulses flip magnetism in stages, the effort needed to show it was not a fluke, and what still blocks a chip-ready version.
Start Here
1. Reshaping the Light, Not the MagnetUnderstand
2. How a Hard Drive Stores a 1 or a 0 3. Optical Switching: Why Light Could Be Far FasterEvaluate
4. Breaking the Three-Layer Barrier 5. How Laser Pulses Flip Magnetism in Stages 6. The Hard Part: Convincing the Field It Was Not a FlukeFinal Take
8. Manohar InsightReshaping the Light, Not the Magnet
Engineers at the University of California San Diego have switched a thicker stack of magnetic material using nothing but light, by changing the shape and size of the laser beam rather than the material itself.
The stack contained nine alternating layers of platinum and cobalt. Earlier experiments had managed optical switching only up to three layers.
The findings, published in Nature Communications, also removed another earlier restriction: the new approach worked without requiring a specific polarization of light.
Senior author Abdoulaye Ndao frames the idea simply: instead of designing a new material to enable optical switching, the team redesigned the light itself.
That is a notable change of strategy. For years the working assumption was that better optical memory would come from better materials. This result argues that the beam is just as much a design variable.
How a Hard Drive Stores a 1 or a 0
Every digital photo, document, and video saved on a hard drive is stored as a vast sequence of 1s and 0s, represented physically by tiny magnetic regions.
That method works, but it has costs. The process consumes substantial energy, and it limits how quickly data can be written.
Both limits matter more every year. Data volumes keep growing, and storage that is faster, denser, and less power-hungry is a constant goal across data centers and consumer devices alike.
The search for an alternative to field-driven writing is therefore not a niche curiosity. It targets a basic bottleneck in how information is physically recorded.
Optical Switching: Why Light Could Be Far Faster
Light offers a different way to write. It can deliver energy in extremely short bursts and concentrate that energy into a very small area.
Those two properties make it a promising tool for switching magnetic states. The approach is called optical switching.
Researchers at UC San Diego estimate that optical switching could be more than 1,000 times faster than approaches that rely on external magnetic fields.
The catch has always been the material. Making optical switching work has meant dealing with restrictions on the magnetic stack, and those restrictions limited how useful the technique could become.
Breaking the Three-Layer Barrier
Ndao explains the old limit directly: past experiments found that increasing the material's thickness beyond three layers suppressed optical switching.
That put a constraint on the overall thickness of the magnetic material and, in turn, on its ability to retain memory over the long term.
| Factor | Earlier Experiments | This Work |
|---|---|---|
| Magnetic layers switched | Up to 3 | 9 (platinum and cobalt) |
| Light polarization | Specific polarization required | Not required |
| Approach | Conventional beam | Reshaped, shrunk ultrafast beam |
The UC San Diego team reshaped and shrunk an ultrafast laser beam, then used it to switch a stack of nine alternating platinum and cobalt layers.
First author Muhammad Waleed Khalid, a Ph.D. student in Ndao's group, describes the idea as optically engineering the light to change the physics happening in the material at the micro- and nanoscale.
How Laser Pulses Flip Magnetism in Stages
The switching is not a single event. It develops over multiple laser pulses.
The first pulses concentrate enough heat into a tiny region to reverse its magnetic state. Subsequent pulses then gradually expand that reversed region until it becomes stable.
That sequence makes the location of the energy important. Controlling where the energy lands helps determine how the switched area forms and grows.
A specialized laser made the control possible. Khalid says it let the team give the beam a certain shape and size, which opened room to explore more fundamental physics than conventional beam lasers allow.
Beam size also ties directly to storage density. In Ndao's words, the smaller the beam, the smaller and denser the optical memory can be.
The source describes the engineered beam as dramatically smaller than those used in earlier approaches. This article does not repeat the source's exact magnitude comparison, because the wording given is too loose to quote as a precise figure.
The Hard Part: Convincing the Field It Was Not a Fluke
The work sits between two research communities that do not usually overlap: optics and thin-film magnetic materials.
Ndao's optics group collaborated with Eric Fullerton, a UC San Diego professor and thin-film magnetic materials expert who holds the endowed chair of the university's Center for Memory and Recording Research.
That pairing let the team approach a long-standing magnetic memory problem through the behavior of light, rather than through new materials alone.
That candor is worth noting. Surprising results in a field often invite skepticism, and repeating the experiments for the optics community was part of earning credibility for the finding.
Other authors include collaborators from additional institutions, including Stéphane Mangin, as listed in the paper.
Shrinking the Beam and Getting the Laser Onto a Chip
The work is a laboratory demonstration, and the researchers are clear about what remains.
Their next step is investigating optical structures that could confine light to even smaller spaces, potentially shrinking the beam to a few hundred nanometers. Those experiments aim to show how engineered light controls magnetism at smaller scales, which matters for packing information more densely.
A practical hurdle sits on the hardware side. Commercial storage devices would need a practical way to produce and deliver the pulses.
The specialized ultrafast laser used in the experiments cannot yet be readily integrated into computer chips.
One possible route the researchers name is to find magnetic materials that produce similar effects with lasers that are easier to incorporate into electronic systems.
The source gives no timeline for a commercial product, no data on write energy, and no storage density figures, so this article does not attach numbers to those questions.
Manohar Insight
The idea I keep coming back to is the inversion. The usual instinct is to fix a limit by changing the material. Here the team left the material alone and changed the light.
That is a good reminder that in physics, both sides of an interaction are design choices. When one side seems stuck, the other may have more room than anyone assumed.
I also respect the honesty about the laser. A specialized ultrafast source that cannot yet sit on a chip is a real gap between a lab result and a product, and the researchers say so instead of glossing over it.
The 1,000-times-faster figure deserves careful reading. It is an estimate of what optical switching could offer, not something this experiment measured. The demonstrated result is switching a nine-layer stack without a polarization requirement.
The detail I would watch is beam size. If light can be confined to a few hundred nanometers and still switch the stack reliably, the density argument becomes much stronger.
The real story is not a faster hard drive. It is a change in where the engineering effort goes: from inventing new magnetic materials to sculpting the light that writes to them.
Join the Signal
If sculpting the light turns out to matter as much as choosing the material, where else in technology might the "other side" of an interaction be the better one to redesign? Share your take in the comments.
#DataStorage #MagneticMemory #OpticalSwitching #Photonics #Spintronics #MaterialsScience #KMManoharInsights
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About the Author
K M Manohar is an independent Sci-Tech writer and research curator who explains breakthrough discoveries that are shaping the future of technology.
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