Structural properties, defects and structural phase transition in the ROFeM (R=La, Nd; M=As, P) materials

TL;DR

This study investigates the structural properties, defects, and phase transitions in layered ROFeM (R=La, Nd; M=As, P) materials using electron microscopy techniques, revealing defect types and temperature-induced structural changes associated with SDW instability.

Contribution

It provides detailed microscopic analysis of defects and phase transitions in ROFeM materials, highlighting the relationship with SDW instability near 150 K.

Findings

Presence of stacking faults and small-angle boundaries in crystals

Structural transitions observed near 150 K related to SDW instability

Complex microstructural changes during in-situ cooling

Abstract

The structural properties of the ROFeM (R=La, Nd; M=As, P) materials have been analyzed by means of electron diffraction, high-resolution transmission-electron microscopy (TEM) and in-situ cooling TEM observations. The experimental results demonstrate that the layered ROFeM crystals often contain a variety of structural defects, such as stacking faults and small-angle boundaries. The in-situ TEM investigations reveal that, in association with the remarkable spin-density-wave (SDW) instability near 150 K, complex structural transitions can be clearly observed in both crystal symmetry and local microstructure features.