Electrical and Magnetoelectrical Transport in FeTe₂ (100) Epitaxial Thin Films

Transition metal dichalcogenides (TMDs) have become one of the most extensively studied materials owing to their rich electrical, magnetic, and optical properties for potential applications in various technological fields. FeTe2, as one of the most important TMD compounds, has attracted much attention because of iron being an earth-abundant transition metal element and physical phenomena predicted for iron-based materials. The magnetic phase transition and magnetoelectrical transport properties related to film thickness in epitaxial FeTe2 thin films are attractive and significant in the understanding of the basic physics of the FeTe2 system at the nanoscale. Here, we study the electrical and magnetoelectrical transport properties of FeTe2 (100) epitaxial films grown on MgO (100) substrates by a molecular beam epitaxy system. Through precisely controlling film thickness at 4, 8, and 12 nm, we find that the epitaxial FeTe2 films exhibit a marcasite phase with an orthorhombic structure and present typical semiconductive transport properties with holes as the majority carrier. The magnetoresistance presents the square-law with B and gradually tends to linear magnetoresistance when the thickness of the FeTe2 film was decreased to 4 nm at 5 K in the low field range, which is mainly ascribed to the gradually disordered domain distribution. The variable range hopping conductive mechanism and the magnetic transition suppression are also revealed and verified by an electrical transport measurement and first-principles calculations.