In a discovery that could offer a new way to control quantum properties in two-dimensional materials, researchers at Cornell have found that electrically sliding the layers of ultrathin graphene can switch the material between distinct magnetic states that persist even after the voltage is removed.

Researchers in the lab of Kenji Yasuda, assistant professor in the School of Applied and Engineering Physics in Cornell Duffield College of Engineering, discovered that when voltage was applied to a four-layer graphene stack, the layers slid into different atomic stacking arrangements, allowing the material to alternate between nonmagnetic and magnetic states, according to the study, published Oct. 14 in Nature Nanotechnology.

The properties of a material depend not only on what atoms are present, but on how they are arranged. Graphite and diamond, for example, are both made of the same atoms, yet their physical properties – color, strength, transparency, conductivity – are vastly different because of different electronic structures between atoms in the materials.

Changing a material’s structure typically requires breaking strong chemical bonds and reconfiguring them in another way, a process that is often time- and energy-intensive, requiring high pressure and high temperature.

“Our goal was to see if we could find an easier way to change the structure of a material that would be more efficient and also have technological utility,” said Yasuda, senior author of the study, who conducted the research with lead author and doctoral student Daniel Brandon.

The group decided to focus on a configuration made up of four layers of the 2D material graphene, a one-atom thick material composed of carbon atoms arranged in a hexagonal layout.

“We discovered that if we focus on the much weaker bonds between the layers, known as van der Waals bonds, we were able to reconfigure the crystal structure,” Yasuda said. “Using voltage, we were able to shift alignment of the layers, something called ‘sliding,’ which changed how the graphene layers were stacked.”

The most stable and common pattern of these layers, or Bernal configuration, corresponded to a nonmagnetic state. Voltage transformed it into the less common and less stable pattern, rhombohedral configuration – a state associated with magnetism, superconductivity and exotic quantum phenomena.

“One of the things that makes this sliding technique interesting is that it is nonvolatile, meaning that the act of sliding and physically moving atoms creates a reliable memory source,” Brandon said. “Once the material is in that state, it persists for a long time and it can go back and forth between the two fairly consistently.”

The researchers said the ability to reversibly change a material’s structure with voltage could provide a new way to design materials whose properties can be rewritten on demand.

“This provides a fundamentally new way to control matter,” Yasuda said. “By electrically rewriting the structure, we may be able to switch not only magnetism, but also superconductivity and other quantum states, opening a path toward reconfigurable quantum materials and new forms of nonvolatile memory.”

Co-authors include doctoral student Yiwen Ai; Akshat Gandhi, M.Eng. ’25; postdoctoral researcher Lujin Min; Kyle Nadel ’28; research intern Peter Golemis; and researchers from Stanford University, Stony Brook University and the National Institute for Materials Science. 

The research was primarily supported by the Basic Energy Sciences program of the U.S. Department of Energy. It was performed in part at the Cornell NanoScale Science and Technology Facility, which is supported by the National Science Foundation, and made use of the Cornell Center for Materials Research shared instrumentation facility.

Diane Tessaglia-Hymes is a communications specialist for Duffield Engineering.