Incipient nodal pairing in planar d-wave superconductors

The possibility of a second pairing transition $d\to d+is$ ($d+i{d}^{\mathrm{\prime }}$) in planar $d$-wave superconductors which occurs in the absence of external magnetic field, magnetic impurities or boundaries is established in the framework of the non-perturbative phenomenon of dynamical chiral symmetry breaking in the system of $2+1$-dimensional Dirac-like nodal quasiparticles. We determine the critical exponents and quasiparticle spectral functions that characterize the corresponding quantum critical behavior and discuss some of its potentially observable spectral and transport features.