Distinct Fe-induced magnetic states in the underdoped and overdoped regimes of La2-xSrxCu1-yFeyO4 revealed by muon spin relaxation

TL;DR

This study investigates how Fe substitution affects magnetic states in La2-xSrxCu1-yFeyO4 across different doping levels, revealing distinct magnetic behaviors in underdoped and overdoped regimes using muon spin relaxation.

Contribution

It provides new insights into Fe-induced magnetic states and their dependence on doping, highlighting a transition from stripe pinning to spin-glass behavior.

Findings

Fe enhances magnetic transition temperature across doping levels.

Underdoped regime shows stripe pinning by Fe.

Overdoped regime exhibits short-range magnetic order and spin-glass state.

Abstract

Zero-field and longitudinal-field muon-spin-relaxation measurements have been performed in partially Fe-substituted La2-xSrxCu1-yFeyO4 in a wide range of hole concentration, to investigate the magnetic state induced by the Fe substitution recently suggested from the neutron-scattering measurements [Phys. Rev. Lett. 107, 127002 (2011)]. It has been found that the magnetic transition temperature is notably enhanced through the 1% Fe substitution in a wide range of hole concentration where superconductivity appears in Fe-free La2-xSrxCuO4. In the underdoped regime, the Fe-induced magnetic order can be understood in terms of the concept of stripe pinning by Fe as in the case of the Zn-induced one in La2-xSrxCu1-yZnyO4. In the overdoped regime, on the other hand, the Fe-induced magnetic order is short-ranged, which is distinct from the stripes. It is plausible that a spin-glass state of Fe spins derived from the Ruderman-Kittel-Kasuya-Yosida interaction is realized in the overdoped regime, suggesting a change of the ground state from the strongly correlated state to the Fermi-liquid state with hole doping in La-214 high-Tc cuprates.