Shubnikov-de-Haas oscillations in topological insulator Bi2Se3 single crystals

Bi2Se3 is an essential thermoelectric semiconductor and a prototypical three-dimensional topological insulator. The as-grown single crystals exhibit hexagonal or reduced trigonal morphology and uniformly flat surfaces down to a few quintuple layers. In this study, we present a comparative analysis of Shubnikov-de Haas (SdH) oscillations and Hall transport measurements conducted under both Physical Property Measurement System (0-14 T) and pulsed high-field (up to 70 T) conditions, aiming to assess whether ultrahigh magnetic fields can enhance surface sensitivity and uncover nonclassical transport features. Across both regimes, we observe a single oscillation frequency and a trivial Berry phase with a 1/8 phase shift, consistent with bulk-dominated transport through a single three-dimensional Fermi pocket. Notably, a deviation from linear Hall resistance as the field strength exceeds 30 T at 1.3 K suggests that the system is entering the 3D bulk quantum limit, where additional transport channels-possibly surface-related-may begin to emerge. While clear topological surface-state signatures are not resolved, our results provide a detailed reference for evaluating the onset of nonclassical behavior in highly doped Bi2Se3. The comparative approach outlined here clarifies the limitations of field-only methods and highlights the necessity of bulk suppression techniques for accessing topological transport in similar systems.