Microwave and superconducting techniques for measurements on unconventional Josephson junctions

The frst part of the thesis describes the instrumentation, testing and analysis of a planar circuit designed for the measurement of the current-phase relationship of niobium-cobalt-insulator-niobium Josephson junctions. A detailed analysis method and fitting routine was developed but the results show that an irreducible mutual inductance places a limit on the accuracy of the chip for the intended measurement. The second part describes a study of the magnetic and microwave properties of a range of thin film niobium coplanar resonators with cobalt and normal metal layers. Magnetic measurements show a magnetic dead layer of 1.3 nm. The observed microwave losses are found to be two orders of magnitude higher than for high quality niobium films. Computer simulation shows that this is mainly due to conductive, rather than magnetic losses, and is in good agreement with the observed proportionality to cobalt thickness. Measurements of the temperature and magnetic field dependence of the losses and resonant frequency as a function of the cobalt thickness show no signs of the oscillatory thickness dependence reported in a number of other experiments. The temperature dependence of all films is found to be in good agreement with Mattis-Bardeen theory

Teaching and learning:an overview of the thematic section

Higher education institutions today operate in a rapidly changing environment and this is undoubtedly reflected in their core functions of teaching and learning. Teaching and learning in higher education are influenced by a well-rehearsed set of global trends such as the changing demography of student populations and higher participation of non-traditional students; growing global interconnectedness and the proliferation of digital media; and an increasing market orientation in higher educatio

Decision support issues in Central and Eastern Europe

Universities in Central and Eastern Europe are caught between enforced data reporting (because the governments want them to account for their activities and performance) and institutional research for strategic development (because universities want to do better). Since the capacity for institutional research is in most universities still fairly limited (there are a few institutional researchers employed and these tend to work with centralized, yet non-integrated information systems), the emphasis of institutional research tends to be more on formal reporting than on supporting decision-making. Given that majority of universities in the region is still predominantly funded by the state, government steering crucially influences university practices. In most of national systems the governments have not developed performance-oriented financing and quality assurance mechanisms that would, in turn, prompt universities to adapt performance-oriented management practices with data analytics as a vital part

Observation of a superconducting glass state in granular superconducting diamond

The magnetic field dependence of the superconductivity in nanocrystalline boron doped diamond thin films is reported. Evidence of a glass state in the phase diagram is presented, as demonstrated by electrical resistance and magnetic relaxation measurements. The position of the phase boundary in the H-T plane is determined from resistance data by detailed fitting to zero-dimensional fluctuation conductivity theory. This allows determination of the boundary between resistive and non-resistive behavior to be made with greater precision than the standard ad hoc onset/midpoint/offset criterion

Fluctuation spectroscopy as a probe of granular superconducting diamond films

We present resistance versus temperature data for a series of boron-doped nanocrystalline diamond films whose grain size is varied by changing the film thickness. Upon extracting the fluctuation conductivity near to the critical temperature we observe three distinct scaling regions -- 3D intragrain, quasi-0D, and 3D intergrain -- in confirmation of the prediction of Lerner, Varlamov and Vinokur. The location of the dimensional crossovers between these scaling regions allows us to determine the tunnelling energy and the Thouless energy for each film. This is a demonstration of the use of \emph{fluctuation spectroscopy} to determine the properties of a superconducting granular system

Superconducting Diamond on Silicon Nitride for Device Applications

Chemical vapour deposition (CVD) grown nanocrystalline diamond is an attractive material for the fabrication of devices. For some device architectures, optimisation of its growth on silicon nitride is essential. Here, the effects of three pre-growth surface treatments, often employed as cleaning methods of silicon nitride, were investigated. Such treatments provide control over the surface charge of the substrate through modification of the surface functionality, allowing for the optimisation of electrostatic diamond seeding densities. Zeta potential measurements and X-ray photoelectron spectroscopy (XPS) were used to analyse the silicon nitride surface following each treatment. Exposing silicon nitride to an oxygen plasma offered optimal surface conditions for the electrostatic self-assembly of a hydrogen-terminated diamond nanoparticle monolayer. The subsequent growth of boron-doped nanocrystalline diamond thin films on modified silicon nitride substrates under CVD conditions produced coalesced films for oxygen plasma and solvent treatments, whilst pin-holing of the diamond film was observed following RCA-1 treatment. The sharpest superconducting transition was observed for diamond grown on oxygen plasma treated silicon nitride, demonstrating it to be of the least structural disorder. Modifications to the substrate surface optimise the seeding and growth processes for the fabrication of diamond on silicon nitride devices

A simple, space constrained NIRIM type reactor for chemical vapour deposition of diamond

In this paper the design of a simple, space constrained chemical vapour deposition reactor for diamond growth is detailed. Based on the design by NIRIM, the reactor is composed of a quartz discharge tube placed within a 2.45 GHz waveguide to create the conditions required for metastable growth of diamond. Utilising largely off-the-shelf components and a modular design, the reactor allows for easy modification, repair, and cleaning between growth runs. The elements of the reactor design are laid out with the CAD files, parts list, and control files made easily available to enable replication. Finally, the quality of nanocrystalline diamond films produced are studied with SEM and Raman spectroscopy, with the observation of clear faceting and a large diamond fraction suggesting the design offers deposition of diamond with minimal complexity

Transkarpatien - Brückenkopf oder Peripherie? Geopolitische und wirtschaftliche Perspektiven einer ukrainischen Region angesichts der EU-Erweiterung

Die multiethnische Region Transkarpatien hat nach Jahrhunderte langer Zugehörigkeit zu Ungarn häufig die politische Zuordnung gewechselt und ist heute eine ukrainische Grenzregion zu Mitteleuropa. Die slawische Bevölkerungsmehrheit der Ruthenen oder Rusinen, die von manchen als eigene, von den Ukrainern verschiedene Nation angesehen wird, die selbstbewusste Minderheit der Ungarn wie auch die nachwirkenden ungarischen Traditionen sowie eine Vielzahl kleinerer ethnischer Gruppen geben dieser Re gion eine starke Identität und die potentielle Funktion eines ukrainischen Brückenkopfs nach Mitteleuropa und zur Europäischen Union (EU). Trotz Grenzhandels und einer recht aktiven Rolle der Ungarn bei der Herstellung grenzüberschreitender Kontakte spielt die Region bi sher aber nur die Rolle einer wirtschaftlich schwachen Peripherie. Ob sie dieser Rolle entwachsen und von der EU-Erweiterung profitieren kann, wird zum großen Teil vom Grenzregime entlang der neuen Außengrenze der EU sowie von der makropolitischen Orientierung der Ukraine abhängen: entscheidet sie sich für eine engere Bindung an die EU oder an Russland? Der Artikel beruht auf einer größeren interdisziplinären Studie und konzentriert sich auf die derzeitigen und möglichen geopolitischen Funktionen der Region.Geopolitical and economic perspectives for a Ukrainian region in view of the EU expansion After centuries of belonging to Hungary, the multiethnic region of Transcarpathia has frequently changed its political affiliation and is now a Ukrainian border region with Central Europe. The Slavic ethnic majority of the Ruthenes or Rusyns, which some see as an independent nation set apart from the Ukrainians, the self-confident minority of Hungarians and the sustained Hungarian traditions as well as the large number of smaller ethnic groups lend the region a strong identity and the potential to act as a Ukrainian bridgehead to Central Europe and the European Union (EU). Despite cross-border trade and a fairly active role by the Hungarians in the establishment of cross-border contacts, the region has to date only fulfilled the function of an economically weak periphery. The question of whether it will be able to grow out of this role and to reap rewards from the EU expansion will to a large part depend on the border regime along the new outermost border of the EU and on the macropolitical orientation of Ukraine: will it decide to maintain closer ties to the EU or to Russia? The article is based on a larger, interdisciplinary study and concentrates on the current and possible geopolitical functions of the region

Design and development of a low temperature, inductance based high frequency ac susceptometer

We report on the development of an induction based low temperature high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K. Careful balancing of the detection coils and calibration have allowed a sample magnetic moment resolution of $5\times10^{-10} Am^2$ at 1 MHz. We will discuss the design and characterization of the susceptometer, and explain the calibration process. We also include some example measurements on the spin ice material CdEr$_2$S$_4$ and iron oxide based nanoparticles to illustrate functionality