Graphene, universality of the quantum Hall effect and redefinition of the SI system

Abstract

The Système Internationale d'unités (SI system) is about to undergo its biggest change in half a century by redefining the units for mass and current in terms of the fundamental constants h and e, respectively. This change crucially relies on the exactness of the relationships which link these constants to measurable quantities. Here we report the first direct comparison of the integer quantum Hall effect in epitaxial graphene with that in GaAs/AlGaAs heterostructures. We find no difference of the quantized resistance value within the relative standard uncertainty of our measurement of 8.6×10 -11 , being the most stringent test of the universality of the quantum Hall effect in terms of material independence.is the measured value from the true value. [International Vocabulary of Metrology,

Tuning carrier density across Dirac point in epitaxial graphene on SiC by corona discharge

“…3 In particular, graphene grown on the Si-face of SiC (SiC/G) has been the material of choice for the fabrication of graphene-based high performance electronic devices such as high-frequency analogue transistors, 4 sensors, 5 and quantum resistance standards. [6][7][8][9][10] In SiC/G, the two-dimensional system is formed by graphene situated on top of a non-conducting buffer carbon layer (the 0-layer), covalently bonded to SiC. Charge transfer between graphene and the localised donor states in the buffer, driven by the work function difference A $ 1 eV, leads to a significant electron density in the as grown SiC/G, typically n $ 10 13 cm À2 .…”

Towards a graphene-based quantum impedance standard

“…Thus, with graphene a highly precise QHR standard working at low magnetic fields and temperatures above 4 kelvin is conceivable, which would be an enormous advantage for practical metrology. In fact, when measuring with direct current (dc), it has been demonstrated already that the precision of the QHE in high quality graphene devices matches that of GaAs devices [6][7][8][9]. However, in the forthcoming fundamental constant-based redefinition of the Système International d'Unités (SI) [10], also the impedance units (capacitance and inductance) will be traced to fundamental constants [11].…”

“…not specially shielded) GaAs devices. They demonstrate that it is indeed promising to develop a graphene-based impedance standard which is much less affected by capacitive effects and can possibly be applied without the elaborate methods required for GaAs, and at the same time can be operated under the same relaxed temperature and magnetic field requirements as are envisioned for the application of graphene as a dc resistance standard [6][7][8][9].The measurements presented in this study were carried out on a large-area Hall bar device (800 µm x 200 µm) lithographically patterned on a graphene film grown on the siliconterminated face of a 4H silicon carbide substrate [15]. The film had been grown in argon at atmospheric pressure, at a temperature of 1650 °C within 5 minutes.…”

“…not specially shielded) GaAs devices. They demonstrate that it is indeed promising to develop a graphene-based impedance standard which is much less affected by capacitive effects and can possibly be applied without the elaborate methods required for GaAs, and at the same time can be operated under the same relaxed temperature and magnetic field requirements as are envisioned for the application of graphene as a dc resistance standard [6][7][8][9].…”

Exploring Video Abstracts in Science Journals: An Overview and Case Study

“…Furthermore, considering the specialization and niche nature of much scientific research, it follows that scholars would be the primary audience for this content, regardless of the platform on which it appears. To illustrate, the most viewed YouTube NJP video abstract in the 56 article sample data set was "Graphene, universality of the quantum Hall effect and redefinition of the SI system," which described a physics related experiment to test the validity of a change in the way mass and electrical current are measured (Janssen, et al, 2011). This particular experiment may be of greatest interest to Journal of Librarianship and Scholarly Communication | jlsc-pub.org JL SC scientists in solid-state physics, a field that, according to the video abstract, has studied the presence of the quantum Hall effect in materials.…”