Electron spin transitions in quantum Hall systems

A system of two-dimensional electron gas in a strong magnetic field exhibit s a remarkable phenomenon known as the fractional quantum Hall effect. Rapi d advances in experimental techniques and intense theoretical work for well over a decade have significantly contributed to our understanding of the m echanism behind the effect. It is now a well established fact that electron correlations are largely responsible for the occurrence of this phenomenon . In recent years, theoretical and experimental investigations have reveale d that those electron correlations, which are responsible for the quantum H all effect, are also the reason for various spin transitions in the system. In this review, we systematically follow the theoretical studies of the ro le spin degree of freedom play in the quantum Hall effect regime and also d escribe several ingenious experiments reported in recent years which are in good agreement with the emerging theoretical picture.