For the first time in the world, a joint research team from NIMS, Nagoya University and The University of Tokyo has successfully observed the transverse Thomson effect—a phenomenon in which metals or semiconductors release or absorb heat when a heat current, charge current and magnetic field are applied orthogonally to each other. This achievement may contribute to advances in physics and materials science related to the conversion between heat, electricity and magnetism, as well as to the development of new thermal management technologies. The research was published in Nature Physics on June 26, 2025.
The Thomson effect—discovered by William Thomson, a pioneer in thermodynamics and electromagnetism—is a fundamental thermoelectric effect, along with the Seebeck and Peltier effects. It is a phenomenon in which metals or semiconductors release or absorb heat when a heat current and charge current are applied in the same direction. These three effects depicted in Figure. a–c are referred to as “longitudinal” thermoelectric effects, which the interconversion between the heat current (or temperature gradient) and charge current in a parallel direction. By contrast, the Nernst and Ettingshausen effects are classified as “transverse” thermoelectric effects, which interconvert heat and charge currents in perpendicular directions. Transverse thermoelectric devices have attracted increasing attention in recent years due to their simpler structures and potential applicability in thermal management (Figure. d–e). All these longitudinal and transverse thermoelectric effects were discovered as early as the 1800s (Figure. a–e). Although materials and devices exhibiting these effects have been actively researched and developed worldwide, the transverse Thomson effect had not been experimentally observed—despite longstanding theoretical expectations of its existence.
The research team applied a heat current, charge current and magnetic field to bismuth–antimony alloys orthogonally to each other. As a result, the team observed heat release and absorption signals with patterns that could not be explained by conventional thermoelectric effects. When the direction of the magnetic field was reversed, heat release switched to heat absorption. This resulting temperature behavior was found to be consistent with predictions of the transverse Thomson effect (Figure. f). This effect—fundamentally distinct from the conventional Thomson effect—can occur only through the simultaneous action of the Nernst and Ettingshausen effects.
The first experimental observation of the transverse Thomson effect represents a major milestone in thermoelectric research. Discovering materials with stronger transverse Thomson effects in future studies could enable the development of technologies capable of actively controlling heat release and absorption in materials and devices by simply reversing the direction of an applied magnetic field.
Nature Physics
Experimental study
Not applicable
Observation of the transverse Thomson effect
26-Jun-2025