Correlation length in cuprates deduced from the impurity-induced magnetization
arXiv:cond-mat/0307728 · doi:10.1103/PhysRevB.70.104515
Abstract
We report a new multi-nuclei based NMR method which allows us to image the staggered polarization induced by nonmagnetic Li impurities in underdoped O6.6 and slightly overdoped O7 YBa2Cu3O6+y above T_C. The spatial extension of the polarization xi_imp approximately follows a Curie law, increasing up to six lattice constants at T=80K at O6.6 in the pseudogap regime. Near optimal doping, the staggered magnetization has the same shape, with xi_imp reduced by a factor 2. xi_imp is argued to reveal the intrinsic magnetic correlation length of the pure system. It is found to display a smooth evolution through the pseudogap regime.
8 latex pages + 8 figures, to appear in Physical Review B, this resubmitted version is twice longer than the previous one : we detail here our method to determine the impurity-induced magnetization