Nuclear quadrupole resonance study of magnetic and nonmagnetic impurities in YBa2Cu4O8

Cu nuclear quadrupole resonance has been used to investigate the effect of nonmagnetic Zn and magnetic Ni impurities on the normal-state properties in the underdoped YBa2Cu4O8 superconducting cuprate. We find that, in contras t to measurements on optimally doped YBa2(Cu1-zZnz)(3)O7-delta, there is no evidence of a complete local suppression of the antiferromagnetic correlat ions about the Zn impurity. There is also no evidence of Ni locally affecti ng the antiferromagnetic correlations. These results have important implica tions for superconductivity theories that assume a local suppression of the antiferromagnetic and superconducting correlations. [S0163-1829(99)13325-3 ].