Researchers discovered topological axion insulators, referred to as ‘holy grail discovery’ which has a potential to open up ways to implement next generation technologies.
A team of researchers led by physicist Arun Bansil discovered a so-called topological axion insulator, a unique state of quantum matter of which researchers previously only theorized existed. Axion insulators are magnetic topological insulators which may exhibit an exotic quantized magnetoelectric effect. An example of an axion insulator is the quantum anomalous Hall (QAH) effect.
Bansil says, “This axion insulating state was realized by combining certain metals and observing their magnetoelectric response. We used a solid state chip composed of manganese bismuth telluride, which were adhered together in two-dimensional layers, to measure the resulting electric and magnetic properties.”
Bansil says they 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,” Bansil says. “It had only been predicted theoretically—now it’s been realized experimentally.”
This discovery could lead to development in spintronic materials which relies upon this manipulation of quantum structure through something called the electron “spin.” Spin, also called angular momentum, describes a fundamental property of electrons defined in one of two potential states: up or down. Electron spins dictate the direction of the magnetic field in the solid.
“Spin batteries of this kind are still largely under development, but scientists believe topological insulators could be the key to unlocking such technology,” Bansil says. “Researchers have proposed spintronics as the way to solve a number of problems with today’s electronics, including issues of power consumption and operational speed in computers and other devices that rely on charge.”
According to the researchers, axion insulators find applications in a wide range of technologies, including sensors, switches, computers, and memory storage devices, among many others. The storage, transportation, and manipulation of magnetic data could become much faster, more robust, and energy-efficient.
The research appeared in the journal Nature.
