Ni-Impurity Effects on Incommensurate Spin Correlations in Superconducting La2-xSrxCuO4 (x=0.06 and 0.07)

TL;DR

This study investigates how Ni impurities influence static spin correlations and incommensurate spin-density modulations in La2-xSrxCuO4 near the superconductor-insulator boundary, revealing changes in spin order and magnetic phases.

Contribution

It provides new insights into impurity effects on spin correlations and phase transitions in LSCO, highlighting the transition from superconducting to antiferromagnetic states with Ni doping.

Findings

Ni reduces incommensurability of SDM

Diagonal SDM volume fraction increases with Ni

Bulk AF order emerges at certain Ni concentrations

Abstract

Neutron scattering experiments have been carried out to explore Ni-impurity effects on static spin correlations in La2-xSrxCuO4 (LSCO) in the vicinity of the superconductor-insulator boundary where both parallel and diagonal spin-density modulations (SDM) coexist at low temperature. Upon dilute Ni substitution the incommensurability decreases for both types of SDM, while the volume fraction of the diagonal (parallel) SDM increases (decreases). Subsequent Ni doping induces a bulk three-dimensional antiferromagnetic (AF) order when x ~ Ni concentration. TN of such the AF order depends on x and seems to disappear at x ~ 0.1. These effects are approximately ascribed by a reduction of mobile holes, and by a transition from the parallel to the diagonal SDM induced by Ni.