Colossal zero-field Nernst effect in topological pentagonal PB 2

The generation of thermoelectric energy based on the anomalous Nernst effect (NE) is of great interest because of its flexibility, simplicity, and low production cost. This phenomenon has been widely studied in ferromagnetic metals, where a large Berry curvature has been associated with pronounced Nernst and anomalous Hall responses. Based on first-principles calculations, we evaluated the anomalous Hall and Nernst conductivities in a two-dimensional monolayer of PB 2 with a pentagonal pattern. We find that this material, a metal exhibiting p -orbital ferromagnetism, displays intense peaks in the Berry curvature arising from avoided band crossings near the Fermi level, resulting in a strong anomalous Nernst response. Additionally, we demonstrate that under biaxial tensile strain, the avoided crossings shift closer to the Fermi level, giving rise to a colossal Nernst response at room temperature that is significantly higher than those reported for most known materials. Specifically, a biaxial tensile strain of 2% allows a maximum Nernst coefficient of 23.9 μ V K − 1 at T = 300 K. A higher strain of 3.5% induces an even greater response of 39.41 μ V K − 1 at T = 100 K. These results indicate an avenue to engineering the thermoelectric response in monolayer penta-PB 2 through moderate mechanical strain.