Magnetic field driven redistribution between extended and localized electronic states in high-mobility Si MOSFETs at low temperatures

In the study of oscillatory electron transport in high-mobility Si MOSFETs at low temperatures we observed two correlated effects in weak in-plane magnetic fields: a steep decrease of the magnetic susceptibility χ(H) and an increase of the concentration of mobile carriers n(H). We suggest a phenomenological model of the magnetic-field-driven redistribution between the extended and localized electronic states that qualitatively explains both effects. We argue that the redistribution is mainly caused by magnetization of the large-spin S ≈ 2 localized states with energies close to the Fermi energy EF , coexisting with the majority Fermi liquid state. Our findings also resolve a long-standing disagreement between the experimental data on χ obtained in weak (H ∼ kBT/μB) and strong (H ∼ EF/gμB) magnetic fields.