Spin susceptibility and spin dynamics at Cu sites in Y Ba₂Cu₄O₈

Abstract

New measurements of the Knight shift tensor K at both Cu sites in the normal conducting state of the 82 K superconductor 1-2-4 are reported. The data are in accordance with a picture where at both Cu sites the Cu valence is close to 2+ and the hole on the plane site is quasi-localized. A significant temperature dependence at plane Cu site is found which is associated with temperature dependent antiferromagnetic fluctuations. Knight shift and spin-lattice relaxation times at Cu plane site are interpreted to be dominated by antiferromagnetic correlations with a temperature dependent correlation length. © 1990.