Structural effects of Mn-substitution in β-FeSe

In the present work the structural and microstructural properties of Mn substituted & beta;-FeSe are inspected by using high-resolution synchrotron X-ray powder diffraction data collected between 10 K and 150 K. It is demonstrated that the thermal increase of the structural strain in the tetragonal phase progressively breaks the 4-fold symmetry at the local scale, qualitatively tracing the development of anisotropy measured in some physical properties, generally ascribed to nematicity. This result points to a close relationship and interplay between structural strain and physical properties; with this notion, the structural strain can be considered as the origin of the unexpected anisotropy observed in some physical properties. Remarkably, incommensurate satellite peaks are observed in the diffraction pattern collected in the low-temperature orthorhombic phase field, likely related to the occurrence of a charge-density-wave instability.

Automated summary

The structural and microstructural properties of Mn substituted β-FeSe were studied using high-resolution synchrotron X-ray powder diffraction. It was found that the thermal increase of structural strain in the tetragonal phase leads to the progressive breaking of 4-fold symmetry at the local scale, which qualitatively traces the development of anisotropy in physical properties, commonly attributed to nematicity. This implies a close relationship and interplay between structural strain and physical properties, suggesting that structural strain may be the origin of unexpected anisotropy in some physical properties. Interestingly, incommensurate satellite peaks were observed in the diffraction pattern collected in the low-temperature orthorhombic phase field, possibly indicating the occurrence of a charge-density-wave instability.