Giant Shubnikov-de Haas oscillations (SdHO) with V-shaped minima are experimentally studied in a high-mobility two-dimensional electron gas based on GaAs/AlGaAs heterostructures. A phenomenological model with two parameters (transport momentum relaxation time ${\tau }_{\text{tr}}$ and quantum scattering time ${\tau }_q$) is developed, accurately describing experimentally measured magnetoresistance over an unexpectedly wide range of magnetic fields (up to $3.5\mathrm{T}$) and temperatures (2–15 K). The model combines: (i) a quasiclassical density of states with a magnetic-field-dependent Gaussian broadening of Landau levels, (ii) a momentum relaxation time scaling with the density of states, and (iii) oscillations of the Fermi level at a fixed electron density. This model reproduces V-shaped oscillation minima with zero-resistance points, a smooth background of positive magnetoresistance, and enables the extraction of ${\tau }_q$ and ${\tau }_{\text{tr}}$ even in microstructures where ballistic and viscous effects dominate at low fields. As expected, the temperature dependence reveals that ${\tau }_{\text{tr}}$ scales inversely with temperature because of acoustic phonon scattering, while ${\tau }_q$ remains temperature independent.

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• Electrical conductivity
• Electrical properties
• High magnetic fields
• Landau levels
• Magnetotransport
• Quantum transport
• Transport phenomena