Wrinkles can be an asset—especially for next-generation electronics. Rice University scientists have discovered that tiny creases in two-dimensional materials can control electrons' spin with record precision, opening the path to ultracompact, energy-efficient electronic devices.
If most devices today use the charge of electrons flowing through silicon to process and encode information, future computing may instead harness spin—a quantum property of electrons that takes on either an "up" or "down" value. Computing with spin could overcome the limitations of current silicon-based technology, reducing the energy footprint of devices and data centers at a moment when computing-driven energy use is soaring globally.
However, spintronics has to contend with a major challenge: Information encoded in spin is quick to decay and can be lost when the electrons in a material scatter and collide with atoms.
In a study published in the journal Matter, Rice materials scientists have reported that bending atomically thin layers of materials like molybdenum ditelluride gives rise to a unique spin texture called persistent spin helix (PSH), which can preserve a spin state even in scattering collisions.
"In typical materials, spin is tied to electron momentum, so changing direction alters spin, whereas in materials with PSH states, spin state remains fixed," said Sunny Gupta, a Rice alumnus and postdoctoral associate who is a first author on the study. "Very few materials in nature can host PSH, making it rare, and until now, hard to fabricate."
The research team led by materials scientist Boris Yakobson hypothesized that wrinkles in 2D materials could be a way to control electron spin states: When a 2D material is bent, the top side of the sheet stretches while the bottom side gets compressed. This uneven strain causes positive and negative charges to shift slightly relative to one another, producing an internal electric field⎯-a phenomenon known as flexoelectric polarization.
To read more, click here.