Superconductivity from spoiling magnetism in the Kondo lattice model

We find evidence that superconductivity intrudes into the paramagnetic-to-magnetic transition of the Kondo lattice model if magnetic frustration is added. Specifically, we study by the variational method the model on a square lattice in the presence of both nearest-neighbor (t) and next-nearest-neighbor (t') hopping of the conduction electrons. We find that, when t'/t > 0, a d-wave superconducting dome emerges between the magnetic and paramagnetic metal phases and close to the compensated regime, i.e., the number of conduction electrons equals the number of localized spin-1/2 moments. Superconductivity is further strengthened by a direct antiferromagnetic exchange, J(H), between the localized moments, to such an extent that we observe coexistence with magnetic order.