63Cu NMR evidence for enhanced antiferromagnetic correlations around Zn impurities in YBa2Cu3O6.7
Doping the high- T(c) superconductor YBa2Cu3O6.7 with 1.5% of nonmagnetic Zn impurities in CuO2 planes is shown to produce a considerable broadening of 63Cu NMR spectra, as well as an increase of low-energy magnetic fluctuations detected in 63Cu spin-lattice relaxation measurements. A model-independent analysis demonstrates that these effects are due to the development of staggered magnetic moments on many Cu sites around each Zn and that the Zn-induced moment in the bulk susceptibility might be explained by this staggered magnetization. Several implications of these enhanced antiferromagnetic correlations are discussed.
Julien
M
Grenoble High Magnetic Field Laboratory, CNRS and MPI-FKF,BP 166, F-38042 Grenoble Cedex 9, France and Laboratoire de Spectrometrie Physique, Universite J. Fourier, BP 87, F-38402 St. Martin d'Heres, France.
Feher
T
Horvatic
M
Berthier
C
Bakharev
ON
Segransan
P
Collin
G
Marucco
J