Temperature derivative of the chemical potential and its magnetooscillations in two-dimensional system

We report first thermodynamic measurements of the temperature derivative of chemical potential ($\partial \mu/\partial T$) in two-dimensional (2D) electron systems. In order to test the technique we have chosen Schottky gated GaAs/AlGaAs heterojunctions and detected experimentally in this 2D system quantum magnetooscillations of $\partial \mu/\partial T$. We also present a Lifshits–Kosevitch type theory for the $\partial \mu/\partial T$ magnetooscillations in 2D systems and compare the theory with experimental data. The magnetic field dependence of the $\partial \mu/\partial T$ value appears to be sensitive to the density of states shape of Landau levels. The data in low magnetic field domain demonstrate brilliant agreement with theory for non-interacting Fermi gas with Lorentzian Landau level shape.