Magnetic properties of spin diluted iron pnictides from muSR and NMR in LaFe1-xRuxAsO

TL;DR

This study investigates how Ru substitution affects the magnetic properties of LaFeAsO, revealing a gradual suppression of magnetic order without inducing superconductivity, and providing insights into the electronic structure changes.

Contribution

It provides a detailed microscopic analysis of Ru doping effects on magnetic order and electronic states in LaFeAsO using muSR and NMR techniques.

Findings

Ru substitution reduces the Néel temperature and magnetic order parameter.

The temperature dependence of 139La NMR relaxation fits a two-band model.

Doping decreases the density of states at the Fermi level as predicted by band structure calculations.

Abstract

The effect of isoelectronic substitutions on the microscopic properties of LaFe1-xRuxAsO, for 0< x< 0.8, has been investigated by means of muSR and 139La NMR. It was found that Ru substitution causes a progressive reduction of the N\`eel temperature (T_N) and of the magnetic order parameter without leading to the onset of superconductivity. The temperature dependence of 139La nuclear spin-lattice relaxation rate 1/T_1 can be suitably described within a two-band model. One band giving rise to the spin density wave ground-state, while the other one is characterized by weakly correlated electrons. Fe for Ru substitution yields to a progressive decrease of the density of states at the Fermi level close to the one derived from band structure calculations. The reduction of T_N with doping follows the predictions of the J_1-J_2 model on a square lattice, which appears to be an effective framework to describe the magnetic properties of the spin density wave ground-state.