Influence of voltmeter impedance on quantum Hall measurements
Influence of voltmeter impedance on quantum Hall measurements
We report the influence of voltmeters on measurements of the longitudinal resistance Rxx in the quantum Hall-effect regime. We show that for input resistances typical of standard digital lock-in amplifiers, Rxx can show a nonzero minimum which might be mistaken for a parallel conduction in the doping layer. This residual …