Quantum oscillations in TaCo₂Te₂ thin flakes

Abstract The ternary transition-metal telluride TaCo 2 Te 2 has been reported to host a topological band structure characterized by a nontrivial Berry phase. While transport properties have been investigated in both bulk crystals and thick flakes (>150 nm), studies on thin flakes (<100 nm) of this van der Waals (vdW) material remain scarce. We investigate the low-temperature transport properties of TaCo 2 Te 2 thin flakes by fabricating Hall bar devices on mechanically exfoliated flakes with different thicknesses (15 nm and 90 nm). Temperature-dependent resistance measurements reveal that the 15-nm-thick sample exhibits a lower residual resistivity ratio and Debye temperature compared to the 90-nm-thick one. Magnetotransport measurements under perpendicular magnetic fields up to ±14 T demonstrate lower magnetoresistance, carrier concentration, and mobility in the thinner sample, suggesting increased phonon scattering due to defect-induced disorder. Remarkably, pronounced Shubnikov–de Haas (SdH) oscillations are observed above 8 T in both samples in spite of the defect-induced disorder. Analysis of the Landau fan diagram yields a non-zero Berry phase in both samples, indicating the existence of a topologically non-trivial phase in TaCo 2 Te 2 thin flakes. Our findings establish TaCo 2 Te 2 as a promising candidate for exploring intrinsic topological states in layered materials.