Correlated transport and spectroscopic investigations of defect‑mediated electronic conduction in Bi2SeTe2

This study investigates the electronic and lattice properties of single-crystalline Bi2SeTe2(BST) to deepen the understanding of its topological behavior and defect-mediated transport mechanisms. Here, we combine results from low-temperature scanning tunneling microscopy and spectroscopy (STM/STS), temperature-dependent transport measurements, and Raman spectroscopy to establish a unified picture of defect-mediated electronic conduction. STM/STS reveal that intrinsic surface defects within the ordered threefold lattice induce nanoscale fluctuations in the Dirac node energy, significantly modulating the local electronic structure. Transport measurements identify variable-range hopping as the dominant conduction mechanism, with a crossover from Mott to Efros-Shklovskii regime at low temperatures. The temperature-dependent Raman anomalies correlate closely with this transport behavior. Together, these multi-probe measurements provide a unified understanding of defect-mediated charge transport in BST and clarify the role of intrinsic disorder in shaping its electronic properties, reinforcing its potential applications in quantum and spintronic devices.