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Epitaxial Graphene On SiC Pushes Quantum Resistance Standard

Accurate realisation of resistance in terms of elementary charge e and the Planck constant h is independent of other factors. researchers say it can therefore be used as a universal standard for resistance
Graphene on SiC has been shown to give an accurate resistance standard and to outperform the presently used GaAs devices in many respects.

Now researchers at MIKES have shown that the measurements can be done at lower magnetic fields and on industrially produced material.

The quantum resistance standard is an ultimate test of materials.

This resistance, based on the quantum Hall effect in two-dimensional structures, allows very accurate realisation of resistance in terms of two fundamental constants of nature: the elementary charge e and the Planck constant h. In this case, it is independent of other factors and may therefore be used as a universal standard for resistance.

Quantum resistance measurements require a high applied magnetic field and a low cryogenic temperature. Earlier precision measurements on graphene have been performed in a magnetic field of about 10 Tesla or more, and at temperatures of about 0.3 Kelvin or below.

The researchers at MIKES have now demonstrated that highly accurate measurements are obtained at lower magnetic fields, in the range from 8 down to 3 Tesla, even when measurement temperature was not less than 1.5 Kelvin.

Using MIKES's self-developed precision resistance bridge based on a cryogenic current comparator (CCC), the correctness of the quantum Hall resistance of the graphene device could be verified with accuracy much better than 1 part per million.

These measurements were performed on industrially produced material supplied by Graphensic AB, Europes first commercial supplier of graphene on SiC that applies a high growth temperature method to produce the graphene.



Graphene-based quantum Hall standard of resistance developed in collaboration between MIKES and Aalto University on graphene supplied by Graphensic AB.

Photolithographic patterning and electrical contacts were made by Aalto University.

"It is very interesting to see how the material and its growth can be pushed to maintain the exceptional properties of graphene," says Alexandre Satrapinski who is in charge of graphene research at MIKES.



Alexandre Satrapinski

 The work was published in the paper, "Precision quantum Hall resistance measurement on epitaxial graphene device in low magnetic field," by A. Satrapinski et al in Applied Physics Letters ,103, (17).

DOI: 10.1063/1.4826641



 



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