A new generation of QHARS: discussion about the technical criteria for quantization

Abstract

New quantum Hall array resistance standards (QHARS) with nominal values in the range from RK/200 to 50RK (i = 2 plateau) have been developed (RK is the von Klitzing constant). The design of the QHARS based on the connection in parallel of Hall bars is made suitable for use in both magnetic field directions. Measurements performed with currents up to 4 mA at 1.3 K show that RK/200 (∼129 Ω) and 16RK/4130 (∼100 Ω) resistance standards have Hall resistances which agree with their nominal values within 5 parts in 109 (1σ). While increasing the temperature, the Hall resistance varies linearly with the longitudinal resistance. Because the sign of this deviation depends on the magnetic field direction, the average of the Hall resistance values measured for both magnetic field directions remains constant within 5 parts in 109 up to 4.2 K. Owing to their large working current, these QHARS have allowed an accurate calibration of a 100 Ω wire resistor using a commercial resistance bridge. An RK/20 (∼1290 Ω) resistance standard made of ten Hall bars placed in parallel by quadruple connections has also been studied. It is found that the resistances measured by using three different voltage terminal pairs agree within 5 parts in 109 in relative value.