The uranium magnetic compound was found to have strong thermoelectric properties, generating four times the transverse stress from heat than the cobalt-manganese-gallium compound that set the last record. This result opens up new potential for actinide elements at the bottom of the periodic table and points to a new direction in the study of topological quantum materials.
The scientists found that the large spin-orbit coupling and strong electronic correlations in the ruthenium-doped uranium-cobalt-aluminum system led to colossal anomalous Nernst conductivity. This shows that uranium and actinide alloys are promising materials for studying the interaction of material topology and strong electron correlations.
The Nernst reaction occurs when a material converts a flow of heat into electrical voltage. This thermoelectric phenomenon can be used in devices that generate electricity from a heat source. The most prominent example is radioisotope thermoelectric generators (RTGs), which use heat from the natural radioactive decay of plutonium-238 to generate electricity – one such RTG currently powers the Mars Perseverance rover on Mars.
“Interestingly, this colossal anomalous Nernst effect appears to be related to the rich topology of the material. This topology is created by the large spin-orbit coupling, which is common in actinides. One of the consequences of the topology of metals is the generation of transverse velocity, which can cause the Nernst reaction. It can also generate other effects, such as new surface states, which can be useful in various quantum information technologies.”
Philip Ronning, Director of the Materials Science Institute at Los Alamos National Laboratory.
The uranium system-generated temperature changes of 23 microvolts per kelvin – four times the previous record that was found in a cobalt-manganese-gallium alloy a couple of years ago and has also been attributed to these topological sources.