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Researchers discovered a significant anomalous Hall effect in the magnetic material SrCo6O11 at temperatures above its magnetic transition, where it exhibits a phenomenon known as the “Spin-Fluctuating Devil’s Staircase.” This observation could revolutionize the design of materials for magneto-thermoelectric conversion, impacting the development of new thermoelectric materials.

Here’s a bit of background: When an electric current flows through a metal sample in a magnetic field, it experiences the Lorentz force. This force generates a voltage perpendicular to the magnetic field and current—a phenomenon referred to as the Hall effect.

In magnetic metals, a similar phenomenon—known as the anomalous Hall effect—may occur independently of an external magnetic field, particularly in ferromagnetic materials wherein electron spins are aligned. Generally, this alignment—and thus the anomalous Hall effect—only manifests below a certain temperature, known as the magnetic transition temperature.

University of California, Irvine scientists recently discovered a one-dimensional nanoscale material whose color changes as temperature changes. The team’s results appeared in Advanced Materials (“Sensitive Thermochromic Behavior of InSeI, a Highly Anisotropic and Tubular 1D van der Waals Crystal”).

“We found that we can make really small and sensitive thermometers,” said Maxx Arguilla, UC Irvine professor of chemistry whose research group led the study. “It’s one of the most applied and translatable works to come out of our lab.”

Arguilla likened the thermometers to “nanoscale mood rings,” referring to the jewelry that changes color depending on the wearer’s body temperature. But instead of simply taking a qualitative temperature reading, the changes in the color of these materials “can be calibrated and used to optically take temperature readings at the nanoscale,” Arguilla said.