In a groundbreaking advancement that could revolutionize the field of thermoelectric research and thermal management technologies, a collaborative team of scientists from the National Institute for Materials Science (NIMS), Nagoya University, and The University of Tokyo have, for the first time worldwide, experimentally observed the elusive transverse Thomson effect. This phenomenon involves the exchange of heat in metals or semiconductors when a heat current, an electric current, and a magnetic field are applied mutually orthogonal to one another—a subtle but profound observation that opens new avenues for controlling energy flow at the intersection of heat, electricity, and magnetism.

The Thomson effect, first discovered by the eminent physicist William Thomson (later Lord Kelvin), is traditionally known as a fundamental thermoelectric effect, alongside the more widely recognized Seebeck and Peltier effects. These classical longitudinal thermoelectric effects involve the interplay of heat and charge currents moving parallel to one another within conductive materials. Historically, these effects have underpinned much of thermoelectric device engineering, focusing on harnessing temperature gradients to generate power or remove heat effectively through electrically driven processes.

In contrast, transverse thermoelectric phenomena involve interactions where heat and electric currents flow perpendicular to each other, leading to distinct effects such as the Nernst and Ettingshausen effects. These transverse effects, while known since the nineteenth century, have garnered increased scientific attention recently due to their simpler mechanical architectures and promising applications in advanced thermal management systems. Despite the theoretical anticipation of a transverse analog to the Thomson effect based on these underlying phenomena, direct experimental evidence remained lacking—until this landmark study.

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The research team strategically utilized bismuth–antimony alloy samples, well-known for their pronounced thermoelectric characteristics, to probe the interplay of heat current, charge current, and magnetic field applied perpendicularly. Precise instrumentation enabled them to detect subtle heat release and absorption signals that deviated starkly from established thermoelectric signatures. Most notably, when the direction of the magnetic field was inverted, the observed heat release switched to heat absorption, incontrovertibly confirming the presence of a transverse Thomson effect.

This phenomenon is fundamentally different from the classical Thomson effect since it arises exclusively from the combined and simultaneous action of the Nernst and Ettingshausen effects—two well-characterized transverse thermoelectric processes. The Nernst effect describes the generation of a transverse electric field in response to a temperature gradient in a magnetic field, while the Ettingshausen effect refers to the creation of a transverse temperature gradient generated by an electric current in the presence of a magnetic field. The intricate synergy of these two effects culminates in the transverse Thomson effect, dictated by orthogonal vectors of heat, charge, and magnetic flux.

Methodologically, the experimental realization required unprecedentedly sensitive thermal measurements and meticulous control of all physical parameters to disentangle the transverse Thomson contribution from competing thermoelectric phenomena. The observed temperature modulations matched well with refined theoretical models, reinforcing confidence in the interpretation. This validation not only confirms a nearly two-century-old theoretical prediction but also expands the taxonomy of thermoelectric effects by adding a transverse counterpart to the Thomson effect.

Looking ahead, this pioneering observation paves the way for innovative thermal technologies that leverage magnetic fields to actively and reversibly manipulate heat flow at microscopic and macroscopic scales. Materials exhibiting stronger transverse Thomson coefficients could be tailored for devices capable of controlled heat release and absorption simply by switching the magnetic field’s polarity. Such capabilities could revolutionize cooling strategies in electronics, precision thermal regulation in sensors, and potentially impact energy conversion methods, enabling more compact, efficient, and versatile thermal management systems.

This discovery is a testament to the relentless progress in material physics and engineering, illustrating how classical concepts can find fresh relevance through contemporary experimental ingenuity. It bridges a critical gap between longstanding theoretical predictions and practical demonstration, enriching our fundamental understanding of thermoelectric phenomena. Moreover, it invites further investigation into the transverse Thomson effect across diverse materials and conditions, potentially uncovering new physics underlying coupled heat, charge, and magnetic interactions.

Beyond fundamental science, the ramifications of this work could extend into applied domains such as spintronics and magnonics, where heat and magnetism intertwine closely. The transverse Thomson effect adds a new dimension to this interplay, offering alternative mechanisms for thermal control and energy harvesting in next-generation functional materials. As researchers dive deeper into that rich parameter space, enhanced theoretical frameworks and sophisticated experimental setups will be crucial to unravel the full potential of transverse thermoelectric effects in practical contexts.

The collaborative nature of this achievement, integrating expertise across institutions and disciplines, highlights the importance of interdisciplinary approaches in uncovering subtle physical effects. Graduate student Atsushi Takahagi, alongside senior researchers Ken-ichi Uchida, Takamasa Hirai, Sang Jun Park, Hosei Nagano, and Abdulkareem Alasli, synthesized their respective specialties in materials science, mechanical engineering, and magnetism to realize this exceptional breakthrough. Their findings were published in the prestigious journal Nature Physics on June 26, 2025, marking a new chapter in thermoelectric research.

The study was supported by significant funding from the JST ERATO UCHIDA Magnetic Thermal Management Materials Project, JSPS Grants-in-Aid for Scientific Research, and fellowships, underscoring the critical investment in foundational materials science. This research not only validates long-discussed theoretical predictions but also galvanizes future explorations aimed at discovering and engineering materials with enhanced transverse thermoelectric responses.

In summary, the experimental observation of the transverse Thomson effect signifies a profound leap forward in the understanding and application of thermoelectric phenomena. By demonstrating the intricate coupling of heat, charge, and magnetic fields under orthogonal configurations, this work unlocks new realms of thermal control, offering exciting prospects for future materials innovation and device miniaturization. The ability to reversibly switch heat release and absorption by magnetic field manipulation brings us closer to sophisticated, actively tunable thermal devices that could transform numerous technological landscapes.

Subject of Research: Not applicable

Article Title: Observation of the transverse Thomson effect

News Publication Date: 26-Jun-2025

Web References: http://dx.doi.org/10.1038/s41567-025-02936-3

Image Credits: Ken-ichi Uchida, National Institute for Materials Science; Hosei Nagano, Nagoya University

Keywords

Transverse Thomson effect, thermoelectric phenomena, Nernst effect, Ettingshausen effect, thermal management, magnetic field, bismuth–antimony alloys, heat current, charge current, thermodynamics, energy conversion, materials science

Tags: energy flow control in materialsexperimental observation of thermoelectric phenomenagroundbreaking scientific discoveriesheat and electricity interactionlongitudinal vs transverse thermoelectric effectsmagnetic field effects on thermoelectricsNIMS Nagoya University collaborationrevolutionary thermal management technologiessemiconductor thermal managementthermoelectric research advancementstransverse Thomson effectWilliam Thomson contributions to thermoelectrics