Abstract: In most of the unconventional superconductors, the quasiparticle excitation spectrum possesses line or point nodes leading to a power-law temperature dependence in the thermodynamic quantities and transport coefficients at low temperatures. In this work we show analytically that an applied weak Zeeman magnetic field can drastically alter these nodal structures. In particular, we predict that surface nodes might be induced on the Fermi surface under certain circumstances. Our numerical calculations of electronic specific heat for selected spin-singlet and spin-triplet states confirm that the change in the nodal structure may accompany significant modification in the power-law temperature dependence.

Key words: superconductivity, nodal structure, Zeeman field, specific heat