2 × 2 Charge Density Wave in FeNbSe Stabilized by Disordered Intercalation.

The complex interplay between electronic and lattice degrees of freedom underlies a rich variety of emergent phenomena in quantum materials, particularly charge density waves (CDWs). Understanding the distinct roles of electron carriers and structural order in CDW formation is crucial for elucidating the underlying mechanisms and enabling control over material properties. The intertwined effects of charge doping and structural periodicity make it challenging to isolate the individual contributions to lattice modulations. Here, we observe a 2 × 2 CDW in FeNbSe stabilized by disordered Fe intercalation. This observation suggests that charge transfer from the disordered Fe intercalation layer plays a key role in stabilizing the 2 × 2 modulation within the NbSe layers. The observation of band and Fermi surface folding provides clear evidence of electronic structure reconstruction induced by the 2 × 2 CDW transition. We note that as the temperature increases, the spectral weight ratio between the folded band and the primary band gradually decreases, a trend consistent with the characteristics of a CDW. Our results demonstrate disorder-induced charge doping as a powerful tool for tailoring electronic properties in two-dimensional materials.