Nonlinear anomalous Nernst effect in strained graphene induced by trigonal warping

Abstract

It has recently been reported that a nonlinear anomalous Nernst current (NANC), induced by Berry curvature near the Fermi surface, can be generated as a second-order response to a longitudinal temperature gradient in a wide variety of time-reversal invariant and noncentrosymmetric materials. So far, NANC in two-dimensional Dirac systems has been reported to be finite only in materials with substantial spin-orbit coupling and titled Dirac cones formed from low-energy Dirac quasiparticles. Here, we prove that NANC can also emerge in two-dimensional Dirac materials even in the complete absence of titled Dirac cones and spin-orbit coupling. It's found that the NANC has a quantum origin from the trigonal warping of the Fermi surface. NANC in both trigonal-warping monolayer and bilayer graphene in the presence of uniaxial strain is theoretically investigated. The magnitude of NANC in trigonal-warping bilayer graphene is comparable to those reported which originated from tilted mechanisms in strained ${\mathrm{MoS}}_{2}$ and bilayer ${\mathrm{WTe}}_{2}$.