Picture a ball. You place it in a landscape with many almost identical valleys. A small tilt one way and it rolls down one valley. A gentle shift in another direction and it rolls down a different one.
This is how Yuita Fujisawa, an assistant professor at Hiroshima University in Japan, explained how magnetism can alter the balance between competing electronic states — causing the electronic arrangement of quantum materials to transform from, say, a striped pattern to a checkerboard pattern.
Fujisawa and colleagues describe the phenomenon in a paper published in the journal Nature Communications, in which they show how magnetism can reorganize the electronic structure of cerium tritelluride (CeTe₃), a quantum material composed of cerium and tellurium atoms that shares certain characteristics with graphene. A second, complementary paper was published in Physical Review B.
“What I find most exciting is that a magnetic field can switch between electronic patterns with different orientations and periodicities,” Fujisawa told Discover. “It is already rare for a single material to host multiple patterns that differ in both their direction and spacing; being able to select among them with a magnetic field is even more unusual.”
Read More: Advanced Quantum Material Curves the Fabric of Space
A Shifting Pattern
The discovery was unexpected. At the time, atomically thin magnetic materials were emerging as a hot topic of research, said Fujisawa, and the team was investigating the electron arrangement in the rare-earth metal CeTe₃ — a two-dimensional layered material.
Using scanning tunneling microscopy (STM), Fujisawa and colleagues determined the arrangement of cerium and tellurium electrons in CeTe₃ at extremely low temperatures. Initially, the electrons appeared in a striped pattern. But when a magnetic field was added, something strange happened.
“I noticed that the pattern present at zero magnetic field had disappeared, which puzzled me. I remember tilting my head in confusion,” said Fujisawa. “Then I realized that a checkerboard pattern had emerged instead, and I was genuinely surprised.”
Frustration and Spin
So, what exactly is happening? The key lies in a concept known as frustration and a quantum property of CeTe₃ called spin.
The researchers explain that while the electrons in the tellurium layer are highly mobile and naturally organize into regimented patterns, the cerium electrons remain highly localized. Thanks to spin, the cerium electrons act like miniature magnets.
In most magnetic systems, there is a direction that enables the spin to minimize its energy. But this is not the case in frustrated magnetic systems — like CeTe₃. Instead, they can form multiple low-energy patterns and display no preference between them.
However, Fujisawa and his team have shown that it is possible to shift the balance between the competing electronic states and alter the pattern (changing it from striped to checkerboard, for example) using a magnetic field.
The Slow And Steady Accumulation Of Science
The study is “a beautiful example of the effectiveness of probing electronic states in quantum materials using STM,” Stephen Blundell, a Professor of Physics who was not involved in the research, told Discover. “The techniques used and developed are all part of the slow and steady accumulation of science that is necessary for science to progress.”
It’s too early to say what the practical application of this research will be, said Fujisawa. “However, the distinctive feature is that a magnetic field switches not only the strength of an electronic state, but also its spatial pattern, including its orientation, periodicity, and symmetry.”
“They might enable multi-state memory or reconfigurable electronic devices — functions that are difficult to achieve with conventional materials,” he added.
In the meantime, he hopes to investigate how the direction of the applied magnetic field influences the magnetic state and explore other material systems.
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Nature Communications: Versatile electronic phases enabled by intertwined multiple frustrations in an antiferromagnetic two-dimensional semimetal
- This article references information from a study published in Physical Review B: Highly fluctuating double-q magnetic order in the van der Waals metal CeTe3
