A crystallographic phase transition within the magnetically ordered state of Ce_2Fe_17

TL;DR

This study reveals a crystallographic phase transition in Ce₂Fe₁₇ within its magnetically ordered state, characterized by a superstructure formation below 118 K, linking magnetic and structural changes.

Contribution

It provides the first direct X-ray diffraction evidence of a phase transition associated with magnetic ordering in Ce₂Fe₁₇, showing a doubling of the unit cell along c.

Findings

Superstructure reflections appear below 118 K

Superstructure involves doubling of the unit cell along c

Superstructure correlates with magnetic ordering

Abstract

X-ray diffraction experiments were performed on polycrystalline and single-crystal specimens of Ce$_{2}$Fe$_{17}$ at temperatures between 10 K and 300 K. Below $T_{\mathrm{t}}$ = 118$\pm$2 K, additional weak superstructure reflections were observed in the antiferromagnetically ordered state. The superstructure can be described by a doubling of the chemical unit cell along the $\mathbf{c}$ direction in hexagonal notation with the same space group $R \bar{3} m$ as the room-temperature structure. The additional antiferromagnetic satellite reflections observed in earlier neutron diffraction experiments can be conclusively related to the appearance of this superstructure.