⁶³Cu and ¹⁹⁹Hg nuclear magnetic resonance was performed on a series of powder HgBa₂CuO₄₊δ samples with different oxygen content δ in order to study the influence of oxygen doping on the spin dynamics in the normal and superconducting state. The spin-lattice relaxation time T₁ of ¹⁹⁹Hg and ⁶³Cu nuclei were measured over a wide range of temperature at different orientations of the crystallites with respect to the magnetic field. For the optimally doped sample (Tc=96 K) we compared our experimental results to numerical calculations of the spin-lattice relaxation rate as a function of temperature below Tc for several types of the order parameter symmetry: isotropic s wave, anisotropic s wave without nodes, s wave with nodes, and d wave, using the different values of the gap parameter 2Δ/kBTc within the AF fluctuation model. The comparison with our experimental relaxation data shows that for ¹⁹⁹Hg nuclei in the orientation B₀∥(a,b) plane as well as for ⁶³Cu nuclei in both orientations, B₀∥(a,b) plane and B₀∥c axis, the experimental results are in coincidence with the dx2₋y2-wave symmetry with the gap parameter 2Δ/kBTc=7.02.

Sprache

Englisch