Transverse Thomson Effect Observed After 170 Years

New Insight Into Heat and Electricity Could Aid Precise Temperature Control

Physicists have finally observed a phenomenon predicted over a century ago, potentially paving the way for more precise localized temperature management. This discovery builds upon the foundational work of a 19th-century scientist.

A Century-Old Prediction Verified

In 1851, **William Thomson**, widely known as **Lord Kelvin**, described how heating or cooling occurs when an electric current flows through a conductor with a temperature difference. The direction of heat flow depends on the current’s alignment with the temperature gradient. This effect, seen in metals like copper and silver, is governed by the material’s Thomson Coefficient.

Scientists have now confirmed a theoretical prediction: the transverse Thomson effect. This occurs at right angles to the electric current, unlike the previously observed effects.

Experimental Breakthrough

Researchers from two Japanese institutes achieved this observation using a bismuth-antimony alloy, a semimetal. They applied an electric current, a temperature gradient, and a magnetic field, all perpendicular to each other.

The team successfully demonstrated that this arrangement can heat or cool the material. Crucially, they found that reversing the magnetic field also reversed the heating or cooling effect.

Understanding the Dynamics

While the transverse Thomson effect was found to be about 15 percent as strong as the original Thomson effect, its intensity may increase in different materials. The underlying mechanism involves electrons congregating more densely in cooler regions, leading to energy release or absorption during their movement.

This phenomenon is distinct from the Joule-Thomson effect, which **Thomson** also co-discovered and relates to gases, not solid conductors.

Potential Applications

Precise temperature control is vital in many modern technologies, from microelectronics to advanced materials processing. For instance, advanced semiconductor manufacturing requires temperature uniformity to within a few nanometers, a level of precision that understanding thermoelectric effects could significantly enhance.

The study detailing this groundbreaking observation has been published in the journal *Nature Physics*.