We investigate the surface oxidation in a van der Waals ferromagnet Fe_3-xGeTe₂, a material widely utilized for spintronic applications. While known for its relative air-insensitivity, exposure to air during the handling process (e.g. device or heterostructure fabrication) can lead to reduction or disappearance of its magnetic signal. Comparison of x-ray absorption and x-ray magnetic circular dichroism spectra between pristine and air-exposed Fe_3-xGeTe₂ confirm a naturally oxidized surface layer on the material. The surface oxide layer has predominantly Fe³⁺ content. X-ray absorption spectroscopy done on micron-sized exfoliated Fe_3-xGeTe₂ flakes reveal that the change in the surface chemical properties can be quite significant for thin flakes. The surface modulation of Fe_3-xGeTe₂ can lead to inaccuracies in characterizing its interfacial magnetic and spin transport properties, and complicate device and heterostructure fabrication processes.

我们研究了范德华铁磁体Fe _3-x GeTe ₂（一种广泛用于自旋电子学应用的材料）中的表面氧化。尽管以其相对的空气不敏感性而闻名，但在处理过程（例如，设备或异质结构制造）过程中暴露于空气中可能导致其磁信号减少或消失。原始和空气暴露的Fe _3-x GeTe ₂之间的x射线吸收和x射线磁性圆二色性光谱的比较证实了材料上自然氧化的表面层。表面氧化物层主要具有Fe ³⁺含量。在微米级剥落的Fe _3-x GeTe ₂上进行的X射线吸收光谱薄片表明，薄薄片的表面化学性质的变化可能非常显着。Fe _3-x GeTe ₂的表面调制可能会导致表征其界面磁和自旋输运特性不准确，并使器件和异质结构的制造工艺复杂化。