Three-dimensional topological insulators have garnered significant attention in scientific research due to their unique electronic properties. An in-depth study has been conducted to explore the influence of iron (Fe) doping on both the magnetic properties and the topological insulating behavior of $\mathrm{S}{\mathrm{b}}_2\mathrm{T}{\mathrm{e}}_3$. Magnetization measurements indicate a magnetic phase transition in the Fe-doped $\mathrm{S}{\mathrm{b}}_2\mathrm{T}{\mathrm{e}}_3$ sample, along with the emergence of superparamagnetic behavior at low temperatures, characterized by an enhanced magnetic moment. Low-temperature $M-H$ curves fitted with the Langevin equation suggest the formation of Fe-induced magnetic clusters within the $\mathrm{S}{\mathrm{b}}_2\mathrm{T}{\mathrm{e}}_3$ matrix. Temperature-dependent muon spin resonance measurements also support the enhancement of magnetic ordering in the doped sample. The low-temperature, low-field magnetoresistance data of the Fe-doped material suggests weak antilocalization (WAL) behavior of the carriers. The signature of WAL is further supported by the Hikami-Larkin-Nagaoka fitting of the low-temperature magnetoconductance data. Density functional theory calculations for both undoped and Fe-doped samples corroborate with the experimental study and reveal an increase in the spin-orbit interaction upon Fe doping. The observation of these phenomena induced by Fe doping underlines the potential of this approach for the development of intrinsic magnetic topological insulators for a broad range of application.

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• Spin-orbit coupling
• Superparamagnetism
• Weak antilocalization
• Topological insulators
• Density functional calculations
• Magnetization measurements
• Muon spin resonance