We analyzed nonexponential 63Cu nuclear spin-lattice relaxation curves for 63Cu-enriched high-Tc superconductors: La 2-xSrxCuO4 with x=0.13 (slightly underdoped) and 0.18 (slightly overdoped), and studied the applicability of an impurity-induced nuclear spin-lattice relaxation theory. We found a remnant of pseudo-spin-gap effect on the host 63Cu nuclear spin-lattice relaxation time and slow inhomogeneous spin fluctuation via the impurity-induced relaxation time. The effect of slow spin dynamics was also observed in 139La nuclear spin-lattice relaxation. The inhomogeneous electron-spin fluctuation, which is associated with randomly distributed staggered moments on the CuO2 plane, smears the pseudo-spin-gap. The fact that the optimal Tc ∼38 K is smaller than T c∼96 K of HgBa2CuO4+δ can be attributed to the depairing effect due to the slow spin fluctuation.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2004 May|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics