CHANGE OF DENSITY-OF-STATES AT FERMI-LEVEL AND SUPERCONDUCTIVITY IN YNI2-X(CO CU)(X)B2C/

The density of states at the Fermi level N(E(F)) was determined from n ormal-state static magnetic-susceptibility measurements on a series of YNi2-x (Co/Cu)(x)B2C compounds. N(E(F)) decreases for both Co and Cu substitution in a manner similar to that observed previously for the s uperconducting transition temperature T-c. However, for a given value of N(E(F)), T-c is significantly higher for Cu than for Co substituted compounds. This indicates that, other than changing N(E(F)), substitu tion also modifies the electron-phonon coupling strength.