Nodeless superconductivity in the noncentrosymmetric Mo3_3Rh2_2N superconductor: a μ\muSR study

The noncentrosymmetric superconductor Mo$_3$Rh$_2$N, with $T_c = 4.6$ K, adopts a $\beta$-Mn-type structure (space group $P$4$_1$32), similar to that of Mo$_3$Al$_2$C. Its bulk superconductivity was characterized by magnetization and heat-capacity measurements, while its microscopic electronic properties were investigated by means of muon-spin rotation and relaxation ($\mu$SR). The low-temperature superfluid density, measured via transverse-field (TF)-$\mu$SR, evidences a fully-gapped superconducting state with $\Delta_0 = 1.73 k_\mathrm{B}T_c$, very close to 1.76 $k_\mathrm{B}T_c$ - the BCS gap value for the weak coupling case, and a magnetic penetration depth $\lambda_0 = 586$ nm. The absence of spontaneous magnetic fields below the onset of superconductivity, as determined by zero-field (ZF)-$\mu$SR measurements, hints at a preserved time-reversal symmetry in the superconducting state. Both TF-and ZF-$\mu$SR results evidence a spin-singlet pairing in Mo$_3$Rh$_2$N.Comment: 5 figures and 5 pages. Accepted for publication as a Rapid Communication in Phys. Rev.

An integrated social media communication view on content marketing by South African non-profit sectors

Background: Organisations widely adopt social media to communicate with stakeholders, yet research into content marketing in the South African non-profit sector is sparse. It is concerned with consistently producing valuable and relevant content for social media. As it is generally associated with the field of marketing, limited research exists from a communication perspective. This perceived gap in taking a communication stance prompted this investigation into the ways in which these organisations attend to social media content aspects. Objectives: The research objective was to acquire a broad understanding of content marketing on social media, unique to South African non-profit organisations. Key areas that were uncovered and statistically verified in an earlier quantitative study and how these are attended to in real life were explored. Method: A qualitative approach was used to obtain in-depth insights into the use of content marketing. Semi-structured interviews were used as data collection method to explore non-profit sector’s approaches to social media communication, and to determine whether their efforts could be regarded as being integrated. Results: The findings yielded valuable insights into the ways that non-profit sectors in South Africa practise social media communication. The benefits of using social media for communication is acknowledged, yet vital aspects such as sourcing content, considering stakeholders’ needs and demographics communication, using available planning tools and recognising employees as internal ambassadors are not considered. Conclusion: The findings of this study highlight several key areas and topics that organisations should consider an integrated social media communication approach as alternative for content marketing in the non-profit secto

Cosmology with Varying Constants

The idea of possible time or space variations of the `fundamental' constants of nature, although not new, is only now beginning to be actively considered by large numbers of researchers in the particle physics, cosmology and astrophysics communities. This revival is mostly due to the claims of possible detection of such variations, in various different contexts and by several groups. Here, I present the current theoretical motivations and expectations for such variations, review the current observational status, and discuss the impact of a possible confirmation of these results in our views of cosmology and physics as a whole.Comment: 14 pages, no figures. Essay to appear in Phil. Trans. Roy. Soc. Lond. A Triennial Series (Christmas 2002 Issue

Simulation of HTS Josephson Mixers

© 2016 IEEE. The Commonwealth Scientific and Industrial Research Organization has developed superconducting microwave monolithic integrated circuit (MMIC) mixers using step-edge Josephson junctions and on-chip filters, made from YBaCuO on MgO substrates. Integration into an MMIC results in a compact and efficiently coupled structure. These have been shown to have outstanding conversion efficiency, dynamic range, and linearity. We report here a range of simulations of this type of mixer. We have mainly used Josephson simulators and analyze the data in both the time and frequency domains. More recently, we have also used microwave simulators incorporating a novel Verilog-A Josephson junction model that we have developed. We have looked at the interactions of junction bias current, local oscillator power, and radio-frequency input power with conversion efficiency, dynamic range, and linearity. Good agreement is found overall with measurements