Nernst effect induced by a Fermi surface nesting instability in a magnetic Weyl semimetal NdAlSi

The thermoelectric Nernst effects are sensitive to details of the electronic structure around the Fermi energy, including the quantum-mechanical Berry phase of the conduction electrons. Here, we quantitatively demonstrate that Nernst effects are significantly enhanced when the Fermi surface has 'hot spots' of scattering time, using a correlated topological semimetal with high carrier mobility in presence of magnetic fluctuations [R. Yamada, Phys. Rev. X (2024)]. Supported by detailed ab-initio calculations and clear quantum oscillations, our thermoelectric measurements on a single crystalline sample of a magnetic Weyl semimetal NdAlSi reveal a drastic enhancement of the Nernst effect in vicinity of a magnetic ordering instability. This work paves the way in the research field of thermoelectric for correlation-driven thermoelectric response independent of a material's carrier density, i.e. in metals, semimetals, and semiconductors with large mobility.