Hall potential distribution in the quantum Hall regime in the vicinity of a potential probe contact

Scanning force microscope measurements of the Hall potential distribution of a two-dimensional electron system (2DES) in the quantum Hall regime reveal the presence of a partial depletion along the border between the 2DES and the good ohmic metal contact: incompressible strips are formed in high magnetic fields along this border, decoupling the bulk region of the 2DES from the contact. This finding clarifies the role of potential probe contacts in Hall bar devices and might affect the interpretation of conductance measurements on Corbino devices.