Muon-spin-relaxation and magnetic-susceptibility studies of effects of the magnetic impurity Ni on the Cu-spin dynamics and superconductivity in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x = 0.13

TL;DR

This study investigates how magnetic Ni impurities affect Cu-spin dynamics and superconductivity in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x=0.13, revealing that Ni requires higher concentrations to induce magnetic order and impacts superconductivity differently than nonmagnetic Zn.

Contribution

It provides detailed muon-spin-relaxation and susceptibility data showing the distinct effects of Ni impurities on magnetic order and superconductivity compared to Zn in high-T_c cuprates.

Findings

Ni requires higher concentration than Zn to stabilize magnetic order.

Ni's pinning of spin correlations is weaker than Zn's.

Zn suppresses superconductivity more effectively than Ni.

Abstract

Effects of the magnetic impurity Ni on the Cu-spin dynamics and superconductivity have been studied in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x = 0.13 changing y finely up to 0.10. Compared with the case of the nonmagnetic impurity Zn, it has been found from the muon-spin-relaxation measurements that a large amount of Ni is required to stabilize a magnetic order of Cu spins. However, the evolution toward the stabilization of the magnetic order with increasing impurity concentration is qualitatively similar to each other. The area of the non-superconducting and slowly fluctuating or static region of Cu spins around Ni has been found to be smaller than that around Zn, suggesting that the pinning of rather long-ranged dynamical spin correlation such as the so-called dynamical stripe by Ni is weaker than that by Zn. This may be the reason why Zn destroys the superconductivity in the hole-doped high-T_c_ cuprates more markedly than Ni.