Charge density wave with suppressed long-range structural modulation in canted antiferromagnetic kagome FeGe

TL;DR

This study investigates the evolution of charge density waves in kagome FeGe across magnetic transitions, revealing a suppressed structural modulation of CDW due to competition with canted antiferromagnetism, using advanced diffraction and microscopy techniques.

Contribution

It uncovers a novel long-range CDW order with suppressed structural modulation in kagome FeGe, highlighting the interaction between CDW and magnetic order.

Findings

Weakening of CDW superlattice reflections after canted AFM transition

Detection of long-range CDW order despite suppressed structural modulation

Identification of Ge dimerization and dynamic CDW domain transformations

Abstract

Kagome lattice can host abundant exotic quantum states such as superconductivity and charge density wave (CDW). Recently, successive orders of A-type antiferromagnetism (AFM), CDW and canted AFM have been manifested upon cooling in kagome FeGe. However, the mechanism of CDW and interaction with magnetism remains unclear. Here we investigate the evolution of CDW with temperature across the canted AFM by single-crystal x-ray diffraction, scanning tunneling microscope (STM) and resonant elastic x-ray scattering (REXS). Interestingly, CDW-induced superlattice reflections become weak after the canted AFM, although long-range CDW order is still detectable by STM and REXS. We uncover a novel long-range CDW order with suppressed structural modulation, likely due to the competition for the underlying crystal structure between CDW and canted AFM. Additionally, occupational modulations of Ge1 in the kagome plane and displacive modulations of all atoms were extracted. The results confirm Ge dimerization along the c axis and suggest a dynamic transformation between different CDW domains.