Superconductivity of heavy fermions in a two-band model

Thermodynamic and electrodynamic properties of heavy-fermion superconductors are studied in a two-band model with interband (“hybrid”) singlet pairing. The general form of electron-electron interaction is analyzed and it is shown in particular that antiferromagnetic spin fluctuations increase the tendency to such a pairing. The expression for the free energy functional is obtained and the behaviour of the correlation length H_c2 and the London penetration depth at T = 0 and T→T_c is investigated. The model discussed gives reasonable qualitative agreement with the properties of heavy-fermion superconductors.