Cryogenic scanning force microscopy of quantum Hall samples: Adiabatic transport originating in anisotropic depletion at contact interfaces

Abstract

Anisotropic magneto resistances and intrinsic adiabatic transport features are generated on quantum Hall samples based on an (Al,Ga)As/GaAs heterostructure with alloyed Au/Ge/Ni contacts. We succeed to probe the microscopic origin of these transport features with a cryogenic scanning force microscope (SFM) by measuring the local potential distribution within the two-dimensional electron system (2DES). These local measurements reveal the presence of an incompressible strip in front of contacts with insulating properties depending on the orientation of the contact/2DES interface line relatively to the crystal axes of the heterostructure. Such an observation gives another microscopic meaning to the term 'non-ideal contact' used in context with the Landauer-Büttiker formalism applied to the quantum Hall effect.

5 pages, 4 figures

References in corpus (2)

• Nonlocal edge state transport in the quantum spin Hall state
• A systematic study of non-ideal contacts in integer quantum Hall systems

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