A contact limited precision of the quantized Hall resistance

A four-terminal Hall resistance is analyzed using the Büttiker formalism of contacts. The possible maximum deviation of a quantized Hall resistance from ideal values in a multiterminal device is shown to be limited by the resistances of contacts. A general expression for the possible maximum deviation is derived for a multiterminal configuration with an arbitrary number of terminals in the condition of an arbitrary (integer) number of filled Landau levels. The influence of an inhomogeneous two-dimensional electron gas on the Hall resistance is also discussed.