Contrasting spin dynamics in Zn- and Ni-doped NdBa_2Cu_3O_(6+y) single crystals from Cu nuclear quadrupole resonance: Evidence for correlations between antiferromagnetism and pseudogap effects

摘要

We report ~(63.65)Cu nuclear quadrupole resonance (NQR) measurements on slightly underdoped NdBa_2Cu_3O_(6+y) heavily doped by Ni and Zn impurities. Owing to the impurity doping, superconductivity is fully suppressed in both cases. The Ni strongly enhances magnetic correlations and induces a wipeout of the NQR signal comparable to that found in stripe ordered lanthanum cuprates. In contrast, the magnetism is suppressed in the Zn doped sample where no wipeout effect is observed and the nuclear spin relaxation rate is reduced. Our findings are in a striking correspondence with the different impact of Ni and Zn impurities on the charge pseudogap evidenced by recent optical data, uncovering thereby a close relationship between the magnetic correlations and pseudogap phenomena.