Magnetotransport properties and Fermi surface topology of GeSb₂Te₄

GeSb₂Te₄ has potential applications in thermoelectrics, memory devices, and quantum information process. Here, we report its electronic properties probed through magnetotransport and magnetic torque measurements. In the zero magnetic field, the electrical resistivity (ρ) exhibits metallic behavior in temperatures (T) between 2 K and 400 K, and follows T² dependence below ~50 K, confirming Fermi liquid ground state. Positive Hall coefficient (R_H) suggests dominant hole-like carriers with carrier concentration of order 10²⁰ cm^-3 at room temperature. Under the application of a magnetic field (H), the resistivity increases with increasing field without sign of saturation up to 35 Tesla at all measured temperatures. Interestingly, the magnetoresistance (MR) falls into a single curve when plotted as a function of H/ρ₀, indicating the system follows Kohler’s rule. By measuring the magnetic torque up to 35 T, we observe de Haas-van Alphen (dHvA) oscillations with three distinct frequencies: F₁ ~ 52 T, F₂ ~ 165 T and F₃ ~ 210 T for H // c. These oscillations persist in all field directions, reflecting 3D nature of the corresponding bands. Lifshitz-Kosevich (LK) analysis of the dHvA oscillations for each frequency reveals small cyclotron effective masses: m₁^* ~ 0.20m₀, m₂^* ~ 0.20m₀ and m₃^* ~ 0.16m₀. By constructing the Landau fan diagram from each oscillation with H aligned at 45º between the c and ab plane, the Berry phase is obtained, which is close to π for all three bands, suggesting nontrivial topology of the Fermi surface. Our findings offer new insights into the topological nature of the Fermi surface of GeSb₂Te₄.