Interplay of weak anti-localization and electron-electron interactions in Sb-alloyed Bi2Te3 nanoparticle system

Three-dimensional topological insulators (3D TIs) like (Bi 1-x Sb x ) 2 Te 3 host robust Dirac surface states, but their transport signatures are often obscured by bulk carriers. Here, we report the synthesis of phase-pure ternary (Bi 1-x Sb x ) 2 Te 3 (x=0-1) nanoparticles via wet-chemical synthesis. Thin pellets composed of the tetradymite-type nanoparticle materials are fabricated by hot pressing and the influence of the Sb-doping level on quantum transport is investigated in detail. Magnetoconductance measurements reveal a pronounced weak anti-localization (WAL) cusp at 1.8 K, attributed to topological surface states. The phase coherence length ( ) decreases from 200 nm (x=0) to 70 nm (x=0.4) with increasing level of Sb-doping, following a power-law dependency ( ), indicating two-dimensional electron-electron interactions (2D EEI) as the dominant dephasing mechanism. Simultaneously, Sb-doping suppresses the onset temperature ( ) of EEI-induced conductance downturn from 20 K (x=0.2) to 5 K (x=0.4). Magnetic field studies show saturation of EEI-driven localization ( ) at magnetic field 2 T, matching with the suppression of topological surface signatures. Our results clearly prove that Sb-doping enables clear recognition of 2D transport physics within a 3D sample, revealing the interplay between WAL and EEI in 3D TIs.