A recent and strange behavior in a particular kind of quantum material could now be explained by a series of buzzing, beelike "loop-currents," according to research from the University of Colorado Boulder.
The study, published on Oct. 12 in Nature, may aid engineers in creating novel gadgets like quantum sensors or the quantum counterpart of computer memory storage.
"Astonishing and Puzzling"
As reported first by Interesting Engineering, the name "honeycomb" refers to the network of interconnecting octahedra formed by the manganese and tellurium atoms in the quantum material, which has the chemical formula "Mn3Si2Te6."
The research began in 2020, and its recent findings are both "astonishing and puzzling," according to Gang Cao, professor in the Department of Physics and corresponding author.
In most circumstances, the material behaved essentially as an insulator. In other words, when the honeycomb was exposed to a magnetic field, it made it impossible for electrical currents to pass through it.
Gang Cao and his associates now believe they can explain such extraordinary behavior.
Based on experiments conducted in Cao's lab, the team claims that under certain conditions, the honeycomb is alive with small internal currents known as chiral orbital currents or loop currents. Electrons zip around in loops within each of the octahedra of this quantum material.
Since the 1990s, it has been hypothesized that several known materials, including high-temperature superconductors, possess such loop currents, but this has not yet been physically verified.
Cao claimed they discovered a new quantum state of matter, with a quantum transition similar to "ice melting into water."
However, the honeycomb in the study differs greatly from those materials; the CMR only takes place when those similar kinds of magnetic polarization are not present.
According to Cao, the change in electrical characteristics is also considerably more dramatic than what is seen in any other CMR material that is currently known. Hence, the team had to find out its root cause.
Loop Currents
Together with Georgia Institute of Technology co-author Itamar Kimchi, they developed the idea of loop currents. The team hypothesized that a great deal of electron motion could be seen tracing the edges of each octahedron inside their honeycombs.
In the absence of a magnetic field, these loop currents often stay chaotic or flow in both clockwise and counterclockwise directions. It resembles vehicles using two lanes of a roundabout at the same time, as per Interesting Engineering.
The researchers said that this instability can create havoc for electrons moving through the material, boosting resistance and turning the honeycomb into an insulator.
"The internal loop currents circulating along the edges of the octahedra are extraordinarily susceptible to external currents," Cao said in a statement.
"When an external electric current exceeds a critical threshold, it disrupts and eventually 'melts' the loop currents, leading to a different electronic state."
But more importantly, Cao claimed that their findings could pave the way for the creation of quantum technologies.
Related Article: Quantum Technology Competition Heats Up as China Has Taken the Lead in Race
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Written by Joaquin Victor Tacla
