Magnetothermoelectricity of anisotropic two-dimensional materials

We use semiclassical Boltzmann transport theory to analytically study the electronic contribution to the linear thermoelectric response of anisotropic two-dimensional materials subjected to a perpendicular magnetic field. Conventional methods, such as the relaxation-time approximation within the Boltzmann formalism, often yield qualitatively incorrect results when applied to anisotropic mediums. On the other hand, the vector mean free path provides exact solutions for the linearized Boltzmann transport equation, and in principle, we can systematically evaluate it to any desired order in the external magnetic field. After laying out the general formalism of the magnetothermoelectric responses of anisotropic systems based on the vector mean free path approach, we study the longitudinal and Hall charge conductivities, as well as the Seebeck and Nernst coefficients of two representative anisotropic two-dimensional electronic systems: a semi-Dirac semimetal and a two-dimensional system of tilted massless Dirac fermions.