Kondo-lattice screening in a d-wave superconductor

We show that local moment screening in a Kondo lattice with d-wave superconducting conduction electrons is qualitatively different from the corresponding single Kondo impurity case. Despite the conduction-electron pseudogap, Kondo-lattice screening is stable if the gap amplitude obeys $\Delta <\sqrt{\tk D}$, in contrast to the single impurity condition $\Delta <\tk$ (where $\tk$ is the Kondo temperature for $\Delta = 0$ and D is the bandwidth). Our theory explains the heavy electron behavior in the d-wave superconductor Nd_{2-x}Ce_{x}CuO_{4}.