D-Wave Kondo Problem in a Square Tight-Bounding Lattice

A Kondo model in a square tight-bonding lattice of conduction electrons is considered. The Kondo interaction takes a d-wave. Using mean-field theory and numerical simulations, it is found that there is a pseudo-gap for the impurity density of states at the Fermi level. Numerical results also show that the exponents of the low-temperature thermodynamic quantities are non-universal but dependent on the interaction.