Frustration-induced diffusive scattering anomaly and dimension change in $\rm FeGe_2$

TL;DR

This study reports a unique checkerboard scattering anomaly in FeGe2 caused by magnetic frustration, revealing a transition from spin dynamics to elastic scattering and indicating emergent two-dimensional magnetic order.

Contribution

The paper introduces a new scattering anomaly in FeGe2 linked to magnetic frustration and proposes a model Hamiltonian including next-nearest neighbor interactions.

Findings

Checkerboard-shaped scattering anomaly observed in FeGe2.

Anomaly appears as spin dynamics at low temperature and elastic scattering above Néel temperature.

Emergence of two-dimensional magnetic order due to magnetic frustration.

Abstract

Magnetic frustration, arising from the competition of exchange interactions, has received great attention because of its relevance to exotic quantum phenomena in materials. In the current work, we report an unusual checkerboard-shaped scattering anomaly in $\rm FeGe_2$, far from the known incommensurate magnetic satellite peaks, for the first time by inelastic neutron scattering. More surprisingly, such phenomenon appears as spin dynamics at low temperature, but it becomes prominent above N\'eel transition as elastic scattering. A new model Hamiltonian that includes an intraplane next-nearest neighbor was proposed and attributes such anomaly to the near-perfect magnetic frustration and the emergence of unexpected two-dimensional magnetic order in the quasi-one-dimensional $\rm FeGe_2$.