April 20, 2024

Colossal voltage results from the interplay of the material’s topology and strong electron correlations in a uranium-cobalt-ruthenium-aluminum alloy.

New research has demonstrated that a magnetic uranium compound can have strong thermoelectric properties, generating four times the transverse voltage from heat than the previous record in a cobalt-manganese-gallium combination. This new research reveals a potential new direction for topological quantum materials research.

“We found that the large spin-orbit coupling and strong electronic correlations in a system of uranium-cobalt-aluminum doped with ruthenium resulted in a colossal anomalous Nernst conductivity,” said Filip Ronning, lead investigator on the paper published on March 26, 2021, in Science Advances. Ronning is the Los Alamos National Laboratory’s Institute for Materials Science director. It shows that actinide and uranium alloys can be used to study the interaction between a material’s topology and strong electron correlations. This interplay is something we are very interested in. We hope to exploit some of the remarkable responses.

Nernst is when a material transforms heat into electric voltage. This thermoelectric phenomenon can also be used to generate electricity from heat sources. Los Alamos is home to radioisotope-thermoelectric generators (RTGs), currently the most prominent example. RTGs use heat from the natural radioactive decay of plutonium-238 to generate electricity–one such RTG is presently powering the Perseverance rover on ” data-gt-translate-attributes='[“attribute”: “data-cm tooltip,” “format”: “html”]’>Mars.

“What’s most exciting about this material is the rich topology. Ronning explained that this topology is caused by large spin-orbit coupling, which is common in actinides. “Topology in metals can lead to transverse velocity generation, which can cause a Nernst reaction, as we see. Other effects can be generated, such as novel surface conditions that could be useful in quantum information technology.

The uranium system studied by the Los Alamos team generated 23 microvolts per kelvin of temperature change–four times more significant than the previous record, which was discovered in a cobalt-manganese-gallium alloy a couple of years ago and also attributed to these sorts of topological origins.

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