text: To explain one variety of this phenomenon, Bertrand Halperin proposed the existence of quasiparticles that live only in two dimensional systems.
full_question: To explain one variety of this phenomenon, Bertrand Halperin proposed the existence of quasiparticles that live only in two dimensional systems. This effect is accompanied by quasi-periodic intervals of zero resistivity and oscillating magnetic moment, two effects named for de Haas. Recent work on graphene has shown this effect at room temperatures, though it was discovered in 2D electron gases created in MOSFETs. It shows that resistance is quantized at units of h over e squared, a constant named for its discoverer Klaus von Klitzing. This effect occurs as the Fermi energy passes discrete Landau levels, and exists in both fractional and integer forms. For 10 points, name this quantum mechanical version of a classical effect in which voltage is produced by a current and magnetic field.
first_sentence: To explain one variety of this phenomenon, Bertrand Halperin proposed the existence of quasiparticles that live only in two dimensional systems.
raw_answer: quantum Hall effect [prompt on "Hall effect"]