Twistronics — the art of stacking ultrathin materials and rotating one layer relative to another to change their electronic behavior — has mostly lived in the laboratory, limited by tiny sample sizes and weak interlayer forces. Now researchers at North Carolina State University report a method to build large-area twisted oxide materials with precise control over the twist angle, joined by strong chemical bonds rather than fragile van der Waals forces.
The team, led by materials scientist Ruijuan Xu, demonstrated the technique with crystalline sodium niobate (NaNbO3) membranes. Using photolithography, they printed visual reference markers around the edges of each membrane, lifted one and placed it on top of another, and watched the markers line up to set the rotation angle. A material-specific annealing step then forged strong chemical bonds between the stacked layers.
'Scale matters for devices,' Xu said. 'Because these crystalline membranes can be fabricated over large areas and transferred onto different supports, this approach provides a practical path toward twist-engineered oxide electronics.' The work is published in the journal ACS Nano.
The measurements revealed something unexpected: the bonds between the layers are so strong they distort the material's atomic structure, creating a gradual rotation of the atomic lattice at the interface and changes to the material's phase structure. Those effects could open 'entirely new interfacial phenomena to explore' and new routes for tailoring materials to specific applications, Xu said. The same method, the researchers believe, could work with other complex oxide materials, turning the dream of practical twistronics from a laboratory curiosity into a platform for next-generation electronics.
