Visualizing Structural Complexities and Different Charge Order Phases in 2D Ferromagnet Fe₅GeTe₂

Pei-Rui Luo^1,2*, Hung-Chang Hsu¹, Hao-Yu Chen³, Xiang-Yu Xie¹, Chia-Nung Kuo⁴, Chin-Shan Lue⁴, Ya-Ping Chiu^1,3

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²School of Medicine, National Taiwan University, Taipei, Taiwan
³Graduate School of Advanced Technology, National Taiwan University, Taipei, Taiwan
⁴Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Pei-Rui Luo, email:parryluo@gmail.com

Two-dimensional (2D) ferromagnetic materials provide a rich platform to study the interplay between electronic and structural properties. In this work, we use scanning tunneling microscopy and spectroscopy (STM/STS) to explore the structural complexities and charge orders (COs) in the 2D van der Waals ferromagnet Fe₅GeTe₂. Our findings reveal multiple CDW phases, including a previously unreported 2×2 modulation coexisting with the well-known √3×√3 periodicity. Each CO phase exhibits distinct electronic characteristics, suggesting the presence of varied charge ordering mechanisms within the material. Additionally, we examine how these periodic modulations interact with the underlying lattice structure, revealing intricate patterns that reflect the complexity of electronic and atomic arrangements. These results offer new insights into the coupling between structural intricacies and electronic orderings in 2D ferromagnets, positioning Fe₅GeTe₂ as a promising candidate for further studies on low-dimensional materials and their emerging intriguing phenomena.

Keywords: 2D Material, Scanning Tunneling Microscopy, Charge Order