SIM.EM – S10 : RMO Comparison final report. High value resistance comparison with twoterminal cryogenic current comparators

This work presents a supplementary comparison of high value resistance standards performed during 2012 and January 2013, following the guidelines presented in a document about measurement comparisons in the CIPM MRA. The purpose of this task was to compare the high resistance cryogenic current comparator scaling of the participating institutes: National Institute of Standards and Technology, USA (NIST), Centro Nacional de Metrología, Mexico (CENAM) and Instituto Nacional de Tecnología Industrial, Argentina (INTI), all of which are members of the Sistema Interamericano de Metrología (SIM) Regional Metrology Organization. All the measurements of this comparison were performed with two-terminal cryogenic current comparators (CCC). Degrees of equivalence of the participating institutes relative to the comparison reference values are given in the report for the measured resistance values.Fil: Bierzychudek, Marcos E. Instituto Nacional de Tecnología Industrial (INTI); ArgentinaFil: Elmquist, Randolph. National Institute of Standards and Technology (NIST); Estados UnidosFil: Hernández, Felipe. Centro Nacional de Metrología (CENAM); Méxic

Quantum Hall effect on centimeter scale chemical vapor deposited graphene films

We report observations of well developed half integer quantum Hall effect (QHE) on mono layer graphene films of 7 mm \times 7 mm in size. The graphene films are grown by chemical vapor deposition (CVD) on copper, then transferred to SiO_{2} /Si substrates, with typical carrier mobilities \approx 4000 cm^{2} /Vs. The large size graphene with excellent quality and electronic homogeneity demonstrated in this work is promising for graphene-based quantum Hall resistance standards, and can also facilitate a wide range of experiments on quantum Hall physics of graphene and practical applications exploiting the exceptional properties of graphene

Two-Terminal and Multi-Terminal Designs for Next-Generation Quantized Hall Resistance Standards: Contact Material and Geometry

In this paper, we show that quantum Hall resistance measurements using two terminals may be as precise as four-terminal measurements when applying superconducting split contacts. The described sample designs eliminate resistance contributions of terminals and contacts such that the size and complexity of next-generation quantized Hall resistance devices can be significantly improved

Accessing ratios of quantized resistances in graphene p–n junction devices using multiple terminals

The utilization of multiple current terminals on millimeter-scale graphene p–n junction devices has enabled the measurement of many atypical, fractional multiples of the quantized Hall resistance at the ν = 2 plateau (RH ≈ 12 906 Ω). These fractions take the form abRH and can be determined both analytically and by simulations. These experiments validate the use of either the LTspice circuit simulator or the analytical framework recently presented in similar work. Furthermore, the production of several devices with large-scale junctions substantiates the approach of using simple ultraviolet lithography to obtain junctions of sufficient sharpness.The utilization of multiple current terminals on millimeter-scale graphene p–n junction devices has enabled the measurement of many atypical, fractional multiples of the quantized Hall resistance at the ν = 2 plateau (RH ≈ 12 906 Ω). These fractions take the form abRH and can be determined both analytically and by simulations. These experiments validate the use of either the LTspice circuit simulator or the analytical framework recently presented in similar work. Furthermore, the production of several devices with large-scale junctions substantiates the approach of using simple ultraviolet lithography to obtain junctions of sufficient sharpness