Oxidation behavior of layered FeGeTe₂ (n = 3, 4, 5) and Cr₂Ge₂Te₆ governed by interlayer coupling

Layered magnetic materials have recently received tremendous attention due to an attractive combination of functional properties suitable for nanoelectronics and spintronic applications. Enhancing the air stability of the material is a prerequisite for long-term durability of devices. However, the oxidation mechanism of layered magnetic materials is yet to be revealed. Herein we explore the oxidation behavior of monolayer and multilayer FeGeTe₂ (n = 3, 4, 5) and Cr₂Ge₂Te₆ using first-principles calculations. The results show that these monolayer systems are prone to be oxidized in ambient air. With increasing thickness, however, multilayer FeGeTe₂ exhibits distinct oxidation behavior from its monolayer counterparts, originating from its unexpected strong interlayer coupling characterized by wavefunction overlapping of adjacent Te atoms between FeGeTe₂ layers. Moreover, O₂ adsorption does not severely deteriorate the magnetism of layered FeGeTe₂ and Cr₂Ge₂Te₆. Given the fact that oxidation properties can be altered by interlayer coupling, our work opens a paradigm for obtaining oxidation-resistant layered materials.