STM imaging and electronic correlation in van der Waals ferromagnet Fe₃GeTe₂

Abstract Fe 3 GeTe 2 is a van der Waals ferromagnet that has attracted significant attention due to its tuneable magnetic properties and potential applications in spintronic devices. In this work, we present a comprehensive study on high-quality Fe 3− x GeTe 2 (FGT) crystals using techniques including scanning tunneling microscopy (STM), atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), superconducting quantum interference device (SQUID) magnetometry, and X-ray magnetic circular dichroism (XMCD). STM and AFM reveal the atomic-scale surface morphology and layer-dependent structural features, highlighting the high crystallinity and terrace structures typical of van der Waals materials. KPFM measurements provide insights into the surface potential distribution and work function variations, indicating electronic structure modifications across different domains. Using the element-specific XMCD technique, we probe the local electronic characteristics of the magnetic ground state of FGT. From sum rule analysis, a significant difference between the orbital and spin moments is observed, leading to a notable spectroscopic splitting factor ( g -factor). Our findings confirm notable contribution of both the Fe 3 d and Ge–Te hybridized orbitals to the overall magnetic properties, shedding light on the microscopic mechanisms governing ferromagnetism in this material. This multi-technique approach provides a detailed understanding of the interplay between structure, electronic properties, and magnetism in FGT, paving the way for future applications in nanoscale magnetic devices.