Ni-substituted sites and the effect on Cu electron spin dynamics of YBa2Cu{3-x}NixO{7-δ}

Abstract

We report Cu nuclear quadrupole resonance experiment on magnetic impurity Ni-substituted YBa${}_2$Cu${}_{3-x}$Ni${}_x$O${}_{7-\delta }$. The distribution of Ni-substituted sites and its effect on the Cu electron spin dynamics are investigated. Two samples with the same Ni concentration $x$=0.10 and nearly the same oxygen content but different $T_c$'s were prepared: One is an as-synthesized sample (7-$\delta$=6.93) in air ($T_c$$\approx 80K$), and the other is a quenched one (7-$\delta$=6.92) in a reduced oxygen atmosphere ($T_c$$\approx 70K$). The plane-site ${}^{63}$Cu(2) nuclear spin-lattice relaxation for the quenched sample was faster than that for the as-synthesized sample, in contrast to the ${}^{63}$Cu(1) relaxation that was faster for the as-synthesized sample. This indicates that the density of plane-site Ni(2) is higher in the quenched sample, contrary to the chain-site Ni(1) density which is lower in the quenched sample. From the analysis in terms of the Ni-induced nuclear spin-lattice relaxation, we suggest that the primary origin of suppression of $T_c$ is associated with nonmagnetic depairing effect of the plane-site Ni(2).

7 pages, 5 figures

References in corpus (2)

• Spin Dynamics near the Superconductor-to-Insulator Transition in Impurity-Doped YBa2Cu4O8
• Cu NQR study of host and guest spin dynamics in impurity-doped YBa2Cu4O8

Cited by in corpus (1)

• Structural, electrical, magnetic, and flux pinning properties of YBCO/Ni superconducting composites: analyses and possible explanations