Cu hyperfine coupling constants of HgBa₂CaCu₂O_6+δ

Abstract

We estimated the ratios of 63 Cu hyperfine coupling constants in the double-layer high-Tc superconductor HgBa2CaCu2O 6+δ from the anisotropies in Cu nuclear spin-lattice relaxation rates and spin Knight shifts to study the nature of the ultraslow fluctuations causing the T2 anomaly in the Cu nuclear spin-echo decay. The ultraslow fluctuations may come from uniform magnetic fluctuations spread around the wave vector q = 0, otherwise the electric origins.

Uniform hole doping in HgBa$_{2}$Ca$_{2}$Cu$_{3}$O$_{8+δ}$ studied by $^{63}$Cu NMR

“…Substituting r u = 0.42 and r AF = 1.7 into (3) and ( 4), we estimated the ratios of the 63 Cu hyperfine coupling constants for the as-synthesized Hg1223 as A cc /4B = −0.59, A ab /4B = −0.03 and A ab /A cc = +0.05. Assuming A ab + 4B = 182 kOe/µ B [39], we obtained the values of A cc = −110, A ab = −5.6, and B = 47 kOe/µ B for the underdoped Hg1223. Cancellation of a relatively large core polarization and a spin dipole field from the 3d x 2 −y 2 orbital can result in the small negative A ab [40].…”