NMR study of the spin dynamics in full over-doped Tl2Ba2CuO y (T c=0 K)

The temperature dependence and the anisotropy of the Knight shift and the spin-lattice relaxation time (T ₁) at the Cu and the O sites of the full over-doped Tl₂Ba₂CuO _y (T _c=0 K: Tl2201L) were measured. The Knight shift values at the Cu and the o sites in the CuO₂ plane are larger in Tl2201L compared to those in Tl₂Ba₂CuO _y (T _c=85 K: Tl2201M). This indicates the increase of the spin part of the Knight shift due to the over-doping. Based on the comparison between theT ₁ in Tl2201L and Tl2201M, the enhancement of the antiferromagnetic correlation still remains in the whole over-doped region.