Detection of Dirac Fermions in Pb1−xSnxTe films tuning the Fermi level via Bi doping

In this study, we systematically investigated Shubnikov–de Haas (SdH) oscillations in Pb 0.5 Sn 0.5 Te samples through controlled bismuth (Bi) doping. The introduction of Bi atoms enabled effective tuning of the Fermi level, allowing access to the linear energy–momentum dispersion characteristic of topological surface states that host Dirac fermions. Experimental magnetotransport data were analyzed using Fast Fourier Transform (F.F.T) techniques in combination with the Lifshitz–Kosevich formalism to extract the relevant quantum oscillation parameters. Our results demonstrate that Dirac fermions emerge when the Fermi level is shifted close to the band edges, highlighting Bi doping as a powerful and reliable method for Fermi-level engineering in the Pb 0.5 Sn 0.5 Te system.