Thermodynamic properties of the phase transitions in a class of spin-triplet ferromagnetic superconductors

Magnetic susceptibility, entropy and specific heat are calculated at the equilibrium points of phase transition to a phase of coexistence of ferromagnetic order and superconductivity in a new class of spin-triplet ferromagnetic superconductors. The results are discussed in view of application to metallic ferromagnets as UGe${}_2$, ZrZn${}_2$, URhGe.