Cu NMR Study of Bilayer HgBa₂CaCu₂O_6+δ ---Variation of Pseudo Spin-Gap Spectrum

抄録

We observed the pseudo spin-gap behavior in the T-dependences of ⁶³Cu Knight shift and NMR relaxation rates, as well as electrical resistivity, over a wide doping range for the bilayer high-T_c HgBa₂CaCu₂O_6+δ using ⁶³Cu NMR spin-echo technique. We found a difference in the doping dependence of the pseudo spin-gap behavior between HgBa₂CaCu₂O_6+δ and the previous monolayer HgBa₂CuO_4+δ. The results indicate that the pseudo spin-gap behavior strongly depends on the underlying electronic states.