Tuning the magnetic and structural phase transitions of PrFeAsO via Fe/Ru spin dilution

TL;DR

This study investigates how substituting Ru for Fe in PrFeAsO influences its structural and magnetic phase transitions, revealing gradual suppression and persistence of magnetic order linked to spin dilution.

Contribution

It provides a detailed phase diagram showing how Ru substitution acts as spin dilution, affecting phase transitions and magnetic order in PrFeAsO.

Findings

Structural transition temperature decreases with Ru content.

Static magnetism persists below the transition temperature.

Magnetic moments vanish at the percolation threshold of the lattice.

Abstract

Neutron diffraction and muon spin relaxation measurements are used to obtain a detailed phase diagram of Pr(Fe,Ru)AsO. The isoelectronic substitution of Ru for Fe acts effectively as spin dilution, suppressing both the structural and magnetic phase transitions. The temperature of the tetragonal-orthorhombic structural phase transition decreases gradually as a function of x. Slightly below the transition temperature coherent precessions of the muon spin are observed corresponding to static magnetism, possibly reflecting a significant magneto-elastic coupling in the FeAs layers. Short range order in both the Fe and Pr moments persists for higher levels of x. The static magnetic moments disappear at a concentration coincident with that expected for percolation of the J1-J2 square lattice model.