ELECTRONIC SPECIFIC-HEAT OF LA(2-X)SR(X)CU(1-Y)M(Y)O(4)(M=GA, ZN) - IMPURITY EFFECTS ON A D-WAVE SUPERCONDUCTOR

The electronic specific heat C-el was studied in Ga- and Zn-doped La2- xSrxCuO4 (0.16 less than or equal to x less than or equal to 0.22) at T less than or equal to 10K. Partial substitution of Ga or Zn for Cu s uppresses T-c and revives the T-linear electronic specific heat, gamma T, markedly. The gamma(y)/gamma(N) vs T-c/T-c0 relation for Zn-doped samples with x greater than or equal to 0.2 is in good agreement with the theoretical one for resonant impurity scattering in a d-wave super conductor, while those for Ga-doped samples and for Zn-doped samples w ith x < 0.2 deviate slightly from the theoretical curve. The deviation will be discussed in relation to changes in the magnetic properties o f 3d electrons.