Magnetotransport in high-g-factor low-density two-dimensional electron systems confined in In0.75Ga0.25As/In0.75Al0.25As quantum wells

We report magnetotransport measurements on high-mobility two-dimensional electron systems (2DESs) confined in In0.75Ga0.25As/In0.75Al0.25As single quantum wells. Several quantum Hall states are observed in a wide range of temperatures and electron densities, the latter controlled by a gate voltage down to values of 1x10(11) cm(-2). A tilted-field configuration is used to induce Landau level crossings and magnetic transitions between quantum Hall states with different spin polarizations. A large filling factor dependent effective electronic g-factor is determined by the coincidence method and cyclotron resonance measurements. From these measurements the change in exchange-correlation energy at the magnetic transition is deduced. These results demonstrate the impact of many-body effects in tilted-field magnetotransport of high-mobility 2DESs confined in In0.75Ga0.25As/In0.75Al0.25As quantum wells. The large tunability of electron density and effective g-factor, in addition, make this material system a promising candidate for the observation of a large variety of spin-related phenomena.