  We investigate symmetry breaking in the Dirac fermion phase of the organic
compound $\alpha$-(BEDT-TTF)$_2$I$_3$ under pressure, where BEDT-TTF denotes
bis(ethylenedithio)tetrathiafulvalene. The exchange interaction resulting from
inter-molecule Coulomb repulsion leads to broken time-reversal symmetry and
particle-hole symmetry while preserving translational symmetry. The system
breaks time-reversal symmetry by creating fluxes in the unit cell. This
symmetry-broken state exhibits a large Nernst signal as well as thermopower. We
compute the Nernst signal and thermopower, demonstrating their consistency with
experimental results.
