Magnetic field dependence of the superconducting gap node topology in non-centrosymmetric CePt3Si

Non-centrosymmetric superconductors, such as CePt3Si and Li2PtB2, are believed to have a line node in the energy gap arising from coexistence of s-wave and p-wave pairing. Using as an example CePt3Si we show that a weak c-axis magnetic field will remove this line node, since it has no topological stability against time-reversal symmetry breaking perturbations. Conversely a field in the a - b plane is shown to remove the line node on some regions of the Fermi surface, while bifurcating the line node in other directions, resulting in two 'boomerang'-like shapes. These line node topological changes are predicted to be observable experimentally in the low temperature heat capacity. (orig.)