Magnetic and Structural Properties of the Iron Oxychalcogenides La$_{2}$O$_{2}$Fe$_{2}$O$M_{2}$ ($M$= S, Se)

TL;DR

This study compares the structural and magnetic properties of La$_{2}$O$_{2}$Fe$_{2}$O$M_{2}$ ($M$= S, Se), revealing similar magnetic ordering and critical behavior despite differences in chalcogen elements.

Contribution

It provides the first detailed magnetic structure analysis of these oxychalcogenides and shows their magnetic interactions are similar despite structural modifications.

Findings

Both materials exhibit antiferromagnetic order with different Neel temperatures.

Magnetic order parameter exponents are close to the Ising value.

Structural similarities persist despite chalcogen exchange.

Abstract

We present the results of structural and magnetic phase comparisons of the iron oxychalcogenides La$_{2}$O$_{2}$Fe$_{2}$O$M$$_{2}$ ($M$ = S, Se). Elastic neutron scattering reveals that $M$ = S and Se have similar nuclear structures at room and low temperatures. We find that both materials obtain antiferromagnetic ordering at a Neel temperature $T_{N}$ 90.1 $\pm$ 0.16 K and 107.2 $\pm$ 0.06 K for $M$= Se and S, respectively. The magnetic arrangements of $M$ = S, Se are obtained through Rietveld refinement. We find the order parameter exponent $\beta$ to be 0.129 $\pm$ 0.006 for $M$ = Se and 0.133 $\pm$ 0.007 for $M$ = S. Each of these values is near the Ising symmetry value of 1/8. This suggests that although lattice and electronic structural modifications result from chalcogen exchange, the nature of the magnetic interactions is similar in these materials.