Demystifying Magnets for Faster, Greener Computing Technology

Much like its functionality, magnetism has a strange history of being pushed away, viewed as limited or solved, only to draw researchers back through technological breakthroughs. By the early 20th century, for instance, magnetism was considered well understood and of low priority for scientists, but a few decades later, it enabled digital computing and made mass digital storage possible with magnetic hard disk drives and non-volatile memory. 

Now, as the rising energy costs of conventional computing are at the forefront of people’s minds, researchers like Roopali Kukreja, an associate professor of materials science and engineering at the University of California, Davis, are turning to magnetism for solutions.

“Magnetism has a history of people thinking it’s not important, then realizing that it is really useful,” Kukreja said. “We are working on magnetic materials that have applications in low-powered devices, with energy efficiency as the big-picture goal.” 

Kukreja has recently had breakthroughs in two projects: one studying the behavior of magnetic materials at ultrafast timescales and the other designing new magnetic alloys.

Through her research, Kukreja aims to harness the physics of magnetism to reshape how information is processed and stored, leading to more efficient computing technologies, a smaller energy footprint and the end of magnets’ push-and-pull pattern for society.

Misbehaving Metals

In one project, Kukreja and her research group are studying the magnetism of cobalt, nickel and platinum multilayers. These metals could be used to develop laser-driven magnetic memory, in which they would be excited by a laser at extremely fast timescales to perform computations.

However, to develop these technologies, researchers and developers need to understand how these metals function at these ultrafast timescales. 

Kukreja and her group set out to do just that. First, they created nanometer-thin films out of the metals and stacked them, alternating cobalt, nickel and platinum films up to approximately 20 layers. 

In the experiments, held at Lawrence Berkeley National Laboratory, or LBNL, and at the Free Electron Laser Radiation for Multidisciplinary Investigations, or FERMI, in Italy, a laser was used to excite the stacked metals at femtosecond timescales (a femtosecond is to one second what one second is to about 31 million years). 

Until recently, the research community assumed that the three metals behaved the same, but using X-ray imaging, Kukreja and her group discovered that the layers behave differently when excited by a laser, contradicting the widely held belief. 

“A lot of magnetism theory is built around the idea that domains are homogeneous through the thickness of the film,” she said. “This is the first time we have shown that they don’t all do the same thing. It was entirely unexpected.”

From a fundamental perspective, this discovery reveals that further research is needed to understand why the metals behave differently when excited. When developing next-generation technologies like laser-driven magnetic memory or storage, it’s important to know whether the layers are communicating correctly.

“If your film is not doing the same thing throughout, then it’s not stable,” Kukreja said. “In hard drives and memory stability is the key.” 

Understanding Magnets for Designer Materials

In another project, Kukreja is focused on high-entropy alloys. These metal combinations are extremely strong, retain their strength at ultra-high temperatures, and have great potential for applications in several areas, including space exploration vehicles, nuclear reactor components and different weight-bearing mechanisms for bikes and electric vehicles.

Researchers at LBNL have proposed that the reason these alloys are so durable is due to how the atoms in the different metals organize themselves at short range. Because magnetic interactions influence how atoms arrange themselves, studying magnetism offers a way to investigate the hidden structures that makes these alloys so strong.

Using LBNL’s X-ray magnetic circular dichroism, or XMCD, technique, Kukreja and her group are setting out to test this hypothesis.

“If it ends up proving true,” she said, “that means you can design a material to have a particular element in a particular way to get whatever properties you want out of it. It’s the beginning of designer materials.”

In a recent paper (currently in preprint), Kukreja and her group showed that, while most metals in high-entropy alloys respond similarly when excited, manganese can flip its alignment, switching from ferromagnetic to antiferromagnetic. Ferromagnetic alignment features parallel spins that create strong net magnetism, while antiferromagnetic alignment features antiparallel spins that cancel each other's magnetization.

This shows that magnetic behavior in complex alloys isn’t the same throughout all the metals, but in fact, it’s element dependent. By further investigating how specific elements in high-entropy alloys drive or suppress magnetization, Kukreja’s research could open a pathway toward tailored magnetic materials that could power spintronic and neuromorphic computing devices. For example, spintronic memory could allow a phone to have terabytes of local storage, while neuromorphic chips could enable a smart sensor in a wearable device to detect anomalies for weeks on a small battery. 

Of course, these findings raise many more questions. Kukreja’s next step is to investigate why manganese behaves that way.

“We have quite a bit of beam time at Lawrence Berkeley in the next six to seven months,” she said.

Into the Unknown

Decades ago, scientists studied electron spin for curiosity’s sake and without any applications in mind. That work later enabled magnetic data storage and spintronic technologies that power modern computing.

With her recent breakthroughs, Kukreja’s work in magnetism is sparking a new conversation — perhaps laying new foundations — about how magnets can pave the way for faster, greener, energy-efficient computing. Kukreja appreciates that gaining knowledge of these minuscule interactions can have huge implications for how the next phase of technology is developed. 

“Understanding the fundamentals is what enables future innovations,” she said. “Plus, it’s really exciting to do this type of research because you’re pushing the boundaries of the unknown.”