Bulk photovoltaic effects of 2D Dirac systems in a temperature gradient

Abstract The bulk photovoltaic effect (BPVE) is the generation of a DC photocurrent in materials that typically requires broken inversion symmetry and plays a crucial role in nonlinear optics and optoelectronics. Here, we theoretically study the BPVE in inversion-symmetric two-dimensional Dirac systems under a temperature gradient, which breaks the inversion symmetry by creating a nonequilibrium steady state. We demonstrate a Drude-like resonant structure in the low-frequency region arising from the jerk and nonlinear Hall processes, and a kink or dip feature in the high-frequency region stemming from the injection and shift processes. Our numerical results indicate that the injection process primarily dominates the BPVE conductivity. Thus, our work proposes an alternative approach for BPVE and highlights potential applications of materials with inversion symmetry in nonlinear optoelectronics.