Giant anomalous Nernst effect in nodal web ferromagnets Fe3_X (X=Ga, Al)

It has recently become clear that band structure topologies, such as Weyl points and nodal lines, are key to enhancing transverse electric and thermoelectric effects, which are respectively beneficial for developing innovative spintronics and thermoelectric applications. Here, we present recently discovered topological magnets, Fe₃X(X=Ga, Al). These materials show a large transverse thermoelectric coefficient of 5.2 A/(Km) at around 200 K and an anomalous Nernst effect of about 6 μV/K at room temperature. We found that these phenomena originate from a nodal web, flat band structure made of interconnected nodal lines near the Fermi energy by performing first-principles calculation. We also succeeded in fabricating thin films of Fe₃X that exhibit a large anomalous Nernst effect at zero field, suitable for designing low-cost, flexible microelectronic thermoelectric generators. (author)