Oscillatory Landé factor of two-dimensional electrons under high magnetic fields

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Using resonant-tunneling spectroscopy in magnetic fields up to 30 T, we have shown that the Land\'e factor g of two-dimensional electrons oscillates with field between its three-dimensional value and a value strongly enhanced by many-body effects. The experiments were carried out at 1.4 K in GaSb-AlSb-InAs-AlSb-GaSb type-II heterolayers, in which holes tunnel resonantly between two GaSb electrodes through magnetic states in the conduction band of an InAs quantum well. The density of these two-dimensional electrons was controlled by the application of external hydrostatic pressure. For the largest electron density (Nₛ=1.2×{}10¹² cm^-2) the g factor oscillated with field between a minimum value of 8 and a maximum of 15. Variations of the same order were observed for lower densities, down to Nₛ=5.2×{}10¹¹ cm^-2. This large enhancement is explained by the exchange interaction between electrons with the same spin.