Anomalous Nuclear Relaxation and Knight Shift Behaviors of ²⁰⁵T1 in High-T_c Tl₂Ba₂Ca₁Cu₂O_8+δ

The nuclear relaxation rate, 1/T₁, and Knight shift have been investigated between 4.2 K and 300 K by ²⁰⁵Tl nuclear magnetic resonance (NMR) for Tl₂Ba₂Ca₁Cu₂O_8+δ with T_c = 100 K. It has been observed that there are two Tl sites possessing a different electronic state. The distinct decrease of 1/T₁ and Knight shift for both Tl sites has been found just below an onset temperature of T₀ = 115 K rather than a zero-resistance temperature of T_c = 100 K. Above T₀, 1/T₁ is not of the Korringa-type with T₁T = const., but exhibits weak temperature dependence, resembling the behavior of the CuO₂ plane site of YBa₂Cu₃O₇. The 1/T₁ for Tl sites possessing no magnetic moments is demonstrated to reflect the strong spin correlation above T₀ through the hybridization with the Cu d-wave function.