Mini array of quantum Hall devices based on epitaxial graphene

TL;DR

This study demonstrates that connecting four epitaxial graphene-based quantum Hall devices in series yields a highly precise quantum resistance standard with deviations below 10^-7, even at relatively low magnetic fields.

Contribution

It presents the first successful series connection of multiple epitaxial graphene QHE devices for a scalable quantum resistance standard with high accuracy.

Findings

Quantum Hall plateaux observed at low magnetic fields (4-5 T)

Series connection of four devices maintains quantization within measurement uncertainty

Deviation from expected resistance was less than 10^-7

Abstract

Series connection of four quantum Hall effect (QHE) devices based on epitaxial graphene films was studied for realization of a quantum resistance standard with an up-scaled value. The tested devices showed quantum Hall plateaux RH,2 at filling factor i = 2 starting from relatively low magnetic field (between 4 T and 5 T) when temperature was 1.5 K. Precision measurements of quantized Hall resistance of four QHE devices connected by triple series connections and external bonding wires were done at B = 7 T and T = 1.5 K using a commercial precision resistance bridge with 50 microA current through the QHE device. The results showed that the deviation of the quantized Hall resistance of the series connection of four graphene-based QHE devices from the expected value of 4*RH,2 = 2h/e^2 was smaller than the relative standard uncertainty of the measurement (< 1*10^-7) limited by the used resistance bridge.