The effects of the surface oxidation on Rare-Earth Tritellurides: Experimental and Theoretical investigation

Two-dimensional (2D) layered rare-earth tritellurides (RTe₃) have gained attention as superconductors and near room-temperature charge density wave materials. Similar to other 2D tellurium-based systems, RTe₃ materials suffer from environmental stability problems. Experimental results show that RTe₃ sheets (with R = La, Nd, Sm, Gd, Dy, and Ho) exposed to air tend to oxidize and form thin TeO_x layers confined to the surface, edges, and grain boundaries. However, the oxidation agents and the characteristics affecting the oxidation resilience are unknown. Therefore, we perform extensive density functional theory (DFT) calculations to study the reactivity of both humidity (H₂O) and oxygen (O₂) on top of pristine and defective LaTe₃ and HoTe₃ monolayers. For pristine RTe₃, we find that oxygen molecules exhibit finite dissociation barriers and strong chemisorption binding energies. Conversely, H₂O is found to play a negligible effect as an aging catalyst. For defective RTe₃ monolayers, we observe 3 to 4 times stronger binding energies of oxygen atoms to the inner R-Te slab. Moreover, the dissociation barriers for H₂O become finite, indicating an enhancement of H₂O molecules’ interaction with the material at the defective sites. In addition, our DFT calculations reveal that in-plane tensile strain can lead to a decrease in the oxidation resilience of RTe₃ materials, which merits further studies.