Tunability of charge density wave in a magnetic kagome metal

TL;DR

This study demonstrates how post-annealing techniques can effectively tune the charge density wave in a magnetic kagome metal, revealing strong coupling between electronic, lattice, and spin properties.

Contribution

It provides a detailed comparison of electronic structures in FeGe with different annealing treatments, highlighting the tunability of the CDW gap and discovering a new low-temperature transition.

Findings

Post-annealing effectively tunes the CDW gap in FeGe.

Long-range CDW order is associated with a new low-temperature transition.

CDW order is highly sensitive to disorder in the kagome lattice.

Abstract

The discovery of the charge density wave order (CDW) within a magnetically ordered phase in the kagome lattice FeGe has provided a promising platform to investigate intertwined degrees of freedom in kagome lattices. Recently, a method based on post-annealing has been suggested to manipulate the CDW order in kagome FeGe towards either long-range or suppressed orders. Here, we provide a comprehensive comparison of the experimentally measured electronic structures of FeGe crystals that have undergone different post-annealing procedures and demonstrate the remarkable effectiveness on tuning the CDW gap without strong perturbation on the underlying electronic structure. Moreover, we observe an additional low temperature transition that only appears in crystals with a long-range CDW order, which we associate with a lattice-spin coupled order. Our work indicates a likely strong sensitivity of the CDW order to disorder in FeGe, and provides evidence for strong coupling between the electronic, lattice, and spin degrees of freedom in this kagome magnet.