In a significant advancement for nanotechnology, scientists from the RIKEN Center for Emergent Matter Science, in collaboration with international colleagues, have unveiled a novel method for fabricating three-dimensional nanoscale devices from single-crystal materials. Utilizing a focused ion beam instrument, the researchers have successfully carved intricate helical-shaped devices from a topological magnet composed of cobalt, tin, and sulfur (Co₃Sn₂S₂), revealing their potential as switchable diodes.
The development, detailed in the journal Nature Nanotechnology, represents a leap forward in the creation of complex nanostructures, which are crucial for the advancement of energy-efficient and compact electronic devices. Until now, the fabrication of such structures was constrained by limited material selection and quality, posing a significant challenge to researchers and engineers alike.
Revolutionizing Nanofabrication
The new method leverages a focused ion beam capable of cutting materials with sub-micron precision, enabling the shaping of three-dimensional devices from virtually any crystal. This technique mirrors the artistry of sculptors, who meticulously chip away at a material block to create intricate forms. By applying this method, the researchers have opened new possibilities for device design and functionality.
To demonstrate the efficacy of their approach, the team crafted helical devices from Co₃Sn₂S₂, a magnetic material known for its unique properties. The devices exhibited a diode effect characterized by nonreciprocal electrical transport, where electric current flows more easily in one direction. This effect could be reversed by altering the magnetization or the chiral handedness of the helix. Moreover, strong current pulses were found to flip the magnetization of the helix, showcasing the dynamic capabilities of these nanoscale diodes.
Implications for Electronic Devices
Diodes are integral components in various electronic applications, including AC/DC conversion, signal processing, and LED devices. The ability to engineer electrical nonreciprocity at the device level through geometric design marks a transformative step in electronic engineering.
Max Birch, the first author of the study, emphasized the significance of this approach:
“By treating geometry as a source of symmetry breaking on equal footing with intrinsic material properties, we can engineer electrical nonreciprocity at the device level. Our newly developed focused ion beam nanosculpting method opens up a wide range of studies on how three-dimensional and curved device geometries can be used to realize new electronic functions.”
Future Prospects and Technological Impact
The intersection of materials physics and advanced nanofabrication techniques heralds a new era in device architecture, with potential applications in memory, logic, and sensing technologies. Yoshinori Tokura, the leader of the research group, highlighted the broader implications:
“More broadly, this approach enables device designs that combine topological or strongly correlated electronic states with engineered curvature in the ballistic or hydrodynamic transport regime. The convergence of materials physics and nanofabrication points to functional device architectures with potential impact on memory, logic, and sensing technologies.”
By comparing helices of varying sizes and temperatures, the researchers traced the diode effect to the asymmetric scattering of electrons from the curved, chiral walls of the devices. This discovery underscores the potential of device shape as a design tool for electronic function, paving the way for low-power, geometry-engineered components in next-generation technologies.
As the field of nanotechnology continues to evolve, the ability to manipulate materials at the nanoscale with such precision and creativity opens up a myriad of possibilities. The focused ion beam technique not only enhances the toolkit available to scientists and engineers but also sets the stage for future innovations that could redefine the landscape of electronic devices.
