Effects of Berry curvature and orbital magnetic moment on the magnetothermoelectric transport of Bloch electron systems

Thermoelectric transport coefficients up to linear order in the applied magnetic field are microscopically studied using Kubo-Luttinger linear response theory and thermal Green’s functions. We derive exact formulas for the thermoelectric conductivity and thermal conductivity in the limit of small relaxation rates for Bloch electrons in terms of Bloch wave functions, which show that the Sommerfeld-Bethe relationship holds. Our final formula contains the Berry curvature contributions as well as the orbital magnetic moment contributions that arise naturally from the microscopic theory. We show that generalized ƒ-sum rules containing the Berry curvature and orbital magnetic moment play essential roles in taking into account the interband effects of the magnetic field. As an application, we study a model of a gapped Dirac electron system with broken time-reversal symmetry and show the presence of a linear magnetothermopower in such systems.