Intrinsic nonlinear Nernst and Seebeck effect

The Nernst and Seebeck effects are crucial for thermoelectric energy harvesting. However, the linear anomalous Nernst effect requires magnetic materials with intrinsically broken time-reversal symmetry. In non-magnetic systems, the dominant transverse thermoelectric response is the non- linear Nernst current. Here, we investigate nonlinear Nernst and Seebeck effects to reveal intrinsic scattering-free Seebeck and Nernst currents arising from band geometric effects in bipartite antiferro- magnets (parity-time-reversal symmetric systems). We show that these contributions, independent of scattering time, originate from the Berry connection polarizability tensor which depends on the quantum metric. Using CuMnAs as a model system, we demonstrate the dominance of intrinsic nonlinear Seebeck and Nernst currents over other scattering-dependent contributions. Our find- ings deepen the fundamental understanding of nonlinear thermoelectric phenomena and provide the foundation for using them to develop more efficient, next-generation energy harvesting devices.