The world of quantum mechanics consists of several mysteries. A new study is one such unraveled mystery that could usher in a new generation of electronic devices.
The study from Northeastern University acts as a ‘holy grail discovery’ in solid-state physics. In this study, scientists focused on an antiferromagnetic axion insulator. In particular, a solid-state chip was used that was composed of two-dimensional manganese bismuth telluride. Scientists then measured the resulting electric and magnetic properties.
They found a type of Hall effect in which electrons from the top and bottom layers spontaneously deflect in opposite directions. Specifically, under zero electric fields, even the manganese bismuth telluride shows no anomalous Hall effect.
When scientists applied an electric field, it created a significant, layer-polarized anomalous Hall effect. This layer Hall effect uncovers an unusual layer-locked Berry curvature, which characterizes the axion insulator state.
In addition, scientists discovered that the layer-locked Berry curvature could be manipulated by the axion field formed from the dot product of the electric and magnetic field vectors.
Scientists think the study has wide implications in several technologies like sensors, switches, computers, memory storage devices, etc. Integration of these new topological materials into future devices could make faster, more robust, and energy-efficient storage, transportation, and manipulation of magnetic data.
Physicist Arun Bansil, who led a team of researchers at Northeastern involved, said, “It’s like discovering a new element. And we know there’s going to be all sorts of interesting applications for this.”
“We selected this specific combination of material, which researchers constructed atom-by-atom in a small crystalline structure because its surface conducts electricity, while the overall structure is largely non-conductive, or insulating—an unusual property that is produced by the strong magnetoelectric coupling of the layers.”
“The topological axion insulator has a miraculous ability that allows it to have very robust metallic or conducting electrons on its surface, even though the bulk of the material is insulating. It had only been predicted theoretically—now it’s been realized experimentally.”
“An emerging class of electronic devices—so-called spintronics—relies upon this manipulation of quantum structure through something called electron “spin.” Spin, also called angular momentum, describes a fundamental property of electrons defined in one of two potential states: up or down. The way the electron’s spin influences the direction of the magnetic field at work in any solid.”
“Whereas traditional electronics depend on batteries that store energy in the form of chemical energy, spintronic devices could harness magnetic energy from special kinds of materials—such as the manganese bismuth telluride chip used in the study—without the chemical reaction, making it much more efficient “candidate material” for future technology.”
“Spin batteries of this kind are still largely under development, but scientists believe topological insulators could be the key to unlocking such technology.”
Scientists have proposed spintronics as the way to solve several problems with today’s electronics, including issues of power consumption and operational speed in computers and other devices that rely on charge.
“There is no question the next generation of electronics will need to have low-power consumption. When you discover new materials like this, that opens up the possibilities. These newer kinds of materials can help usher in entirely new technologies.”
- Gao, A., Liu, YF., Hu, C. et al. Layer Hall effect in a 2D topological axion antiferromagnet. Nature 595, 521–525 (2021). DOI: 10.1038/s41586-021-03679-w