Spin correlation in trigonal EuMn$_{2}$As$_{2}$

TL;DR

This study investigates the magnetic correlations in EuMn₂As₂, revealing two antiferromagnetic transitions and detailed spin arrangements using neutron scattering, highlighting its unique trigonal structure within the pnictide family.

Contribution

It provides the first detailed neutron scattering analysis of EuMn₂As₂, uncovering its magnetic transition sequence and spin configurations in a trigonal structure.

Findings

Two successive antiferromagnetic transitions at 135 K and 14.4 K.

Long-range Mn antiferromagnetic correlations in the a-b plane below 135 K.

Eu spins align with a 55-degree rotation from the c-axis below 14.4 K.

Abstract

The trigonal structure of EuMn$_{2}$As$_{2}$ is an anomaly in the tetragonal 122-type pnictide family. We report detailed investigation of the underlying magnetic correlations in single crystal EuMn$_{2}$As$_{2}$ using high resolution elastic neutron scattering measurements. The system undergoes through two successive antiferromagnetic transitions at $T$ = 135 K and 14.4 K, respectively. Numerical modeling of the experimental data reveals the long range antiferromagnetic correlation of Mn-ions in the $a-b$ plane below $T_N1$ = 135 K. Mn spins are aligned closer to the diagonal axis of the unit cell. The lower temperature transition, below $T_N2$ = 14.4 K, is found to arise due to the long range antiferromagnetic correlation of Eu spins that are rotated by $\theta$ = 55 degree from the $c$-axis of the unit cell.