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|Type:||Artigo de periódico|
|Title:||Magnetic Field Dependence Of The Metal-insulator Transition In Ga[al]as-heterostructures|
Von Waldkirch M.
|Abstract:||A metal-insulator transition at zero magnetic field is observed in Ga[Al]As-heterostructures where a high density of self-assembled InAs-quantum dots is located in the region of the two-dimensional electron gas (2DEG). This transition occurs only in samples with high dot densities. In contrast to other two-dimensional systems showing a metallic phase the Coulomb energy is comparable to the kinetic energy in our systems. Measurements in perpendicular fields reveal that the resistivity at B = 0 is composed of several contributions. In the metallic regime a weak localization peak is superposed on top of a broad negative magnetoresistivity. In the insulating regime, the weak localization peak at B = 0 develops into a very pronounced negative magnetoresistivity with decreasing electron density. Pronounced, almost B-periodic oscillations in the magnetoresistivity are observed in addition to universal conductance fluctuations.|
|Editor:||Elsevier Sci B.V., Amsterdam, Netherlands|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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