Large anomalous Nernst effect and nodal plane in an iron-based kagome ferromagnet

Kagome ferromagnet Fe 3 Sn exhibits large magnetic thermoelectric effect due to Berry curvature enhanced by a nodal plane.

Anomalous Nernst effect dependence on composition in Fe100-X Rh X alloys

We studied the anomalous Nernst effect in CsCl-type Fe100-X Rh X (X = 45, 48, 50, 52, 54, 60) with a thickness of 50 nm deposited on a thermally oxidized Si substrate. Samples with X < 48 certainly have a ferromagnetic phase, exhibiting the anomalous Nernst effect. The composition dependence of the anomalous Nernst coefficient S yx agreed with the transverse thermoelectric conductivity α yx. |S yx | and |α yx | were maximized at X = 48, which has a ferromagnetic state close to the phase transition state. The maximization of |α yx | at X = 48 can be explained using band structure-based calculations , where |α yx | rapidly increases near the phase transition.

Colossal anomalous Nernst effect in a correlated noncentrosymmetric kagome ferromagnet

The transverse voltage generated by a temperature gradient in a perpendicularly applied magnetic field, termed the Nernst effect, has promise for thermoelectric applications and for probing electronic structure. In magnetic materials, an anomalous Nernst effect (ANE) is possible in a zero magnetic field. We report a colossal ANE in the ferromagnetic metal UCo0.8Ru0.2Al, reaching 23 microvolts per kelvin. Uranium’s 5f electrons provide strong electronic correlations that lead to narrow bands, a known route to producing a large thermoelectric response. In addition, uranium’s strong spin-orbit coupling produces an intrinsic transverse response in this material due to the Berry curvature associated with the relativistic electronic structure. Theoretical calculations show that in UCo0.8Ru0.2Al at least 148 Weyl nodes, and two nodal lines, exist within 60 millielectron volt of the Fermi level. This work demonstrates that magnetic actinide materials can host strong Nernst and Hall responses due to their combined correlated and topological nature.