We report on the influence of structural disorder on the electrical properties of multilayer graphene (MLG). Exponential decreases in the conductance and transconductance with increase of defects in the MLG were observed, which could be explained by the percolation and the variable range hopping conduction. An enhancement of p-type nature with increasing disorders was considered to be the result of oxygen doping in the graphene sheets introduced by oxygen plasma. The rapid increase of low-frequency noise was attributed to the formation of conductive network through the continuum percolation, as the low-frequency noise could be increased by the enhanced carrier scattering at the defect sites. We hope that our result should suggest a simple method of tuning the electrical properties of graphene.

We report the design of the KRISS watt balance, which includes a magnet, a guiding stage and a coil position measurement system. The KRISS watt balance incorporates a closed-type cylindrical permanent magnet and a motion guiding stage. For the magnet, a flux shunt is used to reduce flux changes due to temperature variations. A piston gauge is used to achieve linearity in the motion guiding stage. In the weighing mode, the residual force between the weight of the test mass and the Lorentz force generated in a coil is measured by a commercial weighing cell. In the dynamic mode, a linear motor in the motion guiding stage vertically translates the coil and the weighing cell. The in-plane motion of the coil is measured by position sensors, and the out-of-plane motion is measured by single-pass homodyne interferometers.

We report on the fabrication and measurements of a superconducting junction of a single-crystalline Au nanowire, connected to Al electrodes. The current-voltage characteristic curve shows a clear supercurrent branch below the superconducting transition temperature of Al and quantized voltage plateaus on application of microwave radiation, as expected from Josephson relations. Highly transparent (0.95) contacts very close to an ideal limit of 1 are formed at the interface between the normal metal (Au) and the superconductor (Al). The very high transparency is ascribed to the single crystallinity of a Au nanowire and the formation of an oxide-free contact between Au and Al. The subgap structures of the differential conductance are well explained by coherent multiple Andreev reflections (MAR), the hallmark of mesoscopic Josephson junctions. These observations demonstrate that single crystalline Au nanowires can be employed to develop novel quantum devices utilizing coherent electrical transport.

This report describes the first CCM key comparison of realizations of the kilogram definition based on the fixed numerical value of the Planck constant, which came into force on 20 May 2019. The objectives were to determine the level of agreement between realizations of the kilogram using Kibble and joule balances and the X-ray crystal density (XRCD) method and to provide input for the calculation of the first "consensus value" of the kilogram. The consensus value will serve as the basis for an internationally coordinated dissemination of the kilogram which will continue until sufficient agreement between realization experiments has been achieved. The comparison was organized by the BIPM and had seven participants. The BIPM, KRISS, NIST and NRC operated Kibble balances, the NIM used a joule balance and the NMIJ and the PTB participated using 28Si spheres, the masses of which were determined with the XRCD method. These realization methods were used to calibrate 1 kg mass standards under vacuum. The standards were sent (in air) to the BIPM where they were compared under vacuum with each other and with BIPM Pt-Ir working standards. The latter were calibrated (in air) traceable to the International Prototype of the Kilogram (IPK), the mass of which served as the definition of the kilogram until 20 May 2019. The results of the weighings at the BIPM together with the measurement results communicated by the participants allowed comparison of the values attributed to mass standards of 1 kg using the participating realization experiments. The level of agreement between mass determinations with the realization experiments and the BIPM as-maintained mass unit, traceable to the Planck constant through the mass of the International Prototype of the Kilogram can also be deduced. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).