Incommensurate spin correlations induced by magnetic Fe ions substituted into overdoped Bi1.75Pb0.35Sr1.90CuO6+z

TL;DR

This study investigates how Fe doping induces incommensurate spin correlations in overdoped Bi-based cuprate superconductors, revealing unexpectedly large incommensurability related to hole concentration, which suggests a different magnetic mechanism in the overdoped regime.

Contribution

It demonstrates that Fe doping induces large incommensurate spin correlations in overdoped Bi1.75Pb0.35Sr1.90CuO6+z, challenging existing understanding of spin behavior in overdoped cuprates.

Findings

Fe doping induces static incommensurate spin correlations.

The incommensurability delta is approximately 0.2 r.l.u.

Delta correlates with hole concentration p, unlike in other cuprates.

Abstract

Spin correlations in the overdoped region of Bi1.75Pb0.35Sr1.90CuO6+z have been explored with Fe-doped single crystals characterized by neutron scattering, muon-spin-rotation (muSR) spectroscopy, and magnetic susceptibility measurements. Static incommensurate spin correlations induced by the Fe spins are revealed by elastic neutron scattering. The resultant incommensurability delta is unexpectedly large (~0.2 r.l.u.), as compared with delta ~ 1/8 in overdoped superconductor La2-xSrxCuO4. Intriguingly, the large delta in this overdoped region is close to the hole concentration p. This result is reminiscent of the delta ~ p trend observed in underdoped La2-xSrxCuO4; however, it is inconsistent with the saturation of delta in the latter compound in the overdoped regime. While our findings in Fe-doped Bi1.75Pb0.35Sr1.90CuO6+z support the commonality of incommensurate spin correlations in high-Tc cuprate superconductors, they also suggest that the magnetic response might be dominated by a distinct mechanism in the overdoped region.