Superlattices and Microstructures, Vol. 22, No. 4, 1997 Current distribution in the integer quantum Hall effect: The role of bulk states Eyal Yahel, Alexander Palevski School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel Hadas Shtrikman Department of Condensed Matter, The Weizmann Institute of Science, Rehovot 76100, Israel (Received 15 July 1996) The role of bulk and edge currents in a two-dimensional electron gas under the conditions of the integer quantum Hall effect (IQHE) was studied by means of an inductive coupling to Hall bar geometry. From this study we conclude that the extended states at the bulk of the sample below the Fermi energy are capable of carrying a substantial amount of Hall current. For Hall bar geometry sample with a back gate we demonstrated that injected current can be pushed from one edge to another by reversing the direction of the external magnetic field. c  1997 Academic Press Limited Key words: electron transport, integer quantum Hall effect, GaAs, heterostructures, current distribution. 1. Introduction Since the discovery of the integer quantum Hall effect (IQHE) [1], the role of bulk [2, 3] versus edge [4–6] states has been discussed theoretically. The results of many experiments [7–11] addressing this issue seem to favor the edge picture over the bulk one. However, recent experimental studies [12–15] revived this controversial question by giving examples supporting the bulk picture. In these studies it has been shown that the electrostatic potential varies in the bulk of the sample. It implied the existence of Hall current carried by the bulk states. In order to address the questions concerning the role of edge versus bulk states in the IQHE we employed an inductive coupling technique [16]. Our method utilizes a small pick-up coil in order to measure time- dependent magnetic fields induced by alternating currents in the sample. Although the sensitivity limitations of this method do not allow for a precise determination of the spatial distribution of the injected current, a quantitative analysis of our data allowed us to reaffirm the following conclusion for Corbino geometry. In the IQHE regime the bulk states at the Fermi energy are localized. However, the bulk states at the Landau levels, below the Fermi energy, may carry a substantial amount of the Hall current. The contribution of these bulk states to the Hall current depends on the details of the electrostatic potential. The latter is strongly influenced by the geometry of the sample and by the attached contacts. These results were obtained for Corbino geometry [16]. In this paper we prove that the same conclusions are valid to a Hall bar geometry as well. 0749–6036/97/080537 + 04 $25.00/0 sm960489 c  1997 Academic Press Limited