Two-dimensional electron systems have been studied for nearly 40 years, and have yielded a number of important discoveries of physical phenomena that directly reflect the quantum mechanical nature of our world. These experiments involved unusually high quality samples, allowing measurements at considerably lower electron densities than had been possible in the past. The results were first viewed with considerable skepticism, but the findings were soon confirmed in other laboratories, and then for other materials. Rather than being a small perturbation, as previously assumed, Coulomb interactions instead provide the dominant energy in these very dilute systems. Strongly interacting systems of electrons in 2-dimensions are currently the focus of intense interest, with numerous theoretical attempts to account for the presence and nature of the conducting phase.
Most theories postulate esoteric new states of matter.
Some theories attribute the unusual behavior to effects that are essentially classical in nature. Although some researchers may strongly advocate a particular view, all would agree that no consensus has been reached. Novel phenomena in dilute electron systems in two dimensions. In classical physics, the Hall effect is the development of a transverse voltage across a current-carrying conductor in a magnetic field, the voltage being perpendicular to both the direction of the current and the direction of the magnetic field. Both quantum Hall effects were first noted in the 1980s.