Periodicity-dependence of the ferroelectric properties in BiFeO3/SrTiO3 multiferroic superlattices

Artificial superlattices of (BiFeO3)m(SrTiO3)m (m= 1 to 10 unit cells) consisting of multiferroic BiFeO3 and insulating SrTiO3 layers were fabricated on (100)-oriented SrTiO3 substrates by pulsed laser ablation. The remnant polarization and leakage current behavior were studied varying the periodicity (8-80A) of the superlattice. The leakage current was reduced by few orders of magnitude on increase of periodicity compared to single layer BiFeO3 thin films. Reduced leakage and intrinsic polarization hysteresis was observed and was confirmed by PUND analysis for periodicities in the range 20-60A. The leakage current was observed to be dominated by space charge limited conductionComment: Submitted to Applied Physics Letter

Transforming digital collections into linked data: The rise of missing links

Goals Study the feasibility of developing a common process that would allow the conversion of our collection records into linked data preserving their original expressivity and richness Publish data from our collections in the Linked Open Data Cloud to improve discover-ability and connections with other related data sets on the We

Characterisation of an n-type segmented BEGe detector

A four-fold segmented n-type point-contact "Broad Energy" high-purity germanium detector, SegBEGe, has been characterised at the Max-Planck-Institut f\"ur Physik in Munich. The main characteristics of the detector are described and first measurements concerning the detector properties are presented. The possibility to use mirror pulses to determine source positions is discussed as well as charge losses observed close to the core contact

Trions in a periodic potential

The group-theoretical classification of trion states is presented. It is based on considerations of products of irreducible representations of the 2D translation group. For a given BvK period N degeneracy of obtained states is N^2. Trions consist of two identical particles so the symmetrization of states with respect to particles transposition is considered. Completely antisymmetric states can be constructed by introducing antisymmetric spin functions. Two symmetry adapted bases are considered. The third possibility is postponed for the further investigations.Comment: revtex, 5 p., sub. to Physica

Bipolar-Driven Large Magnetoresistance in Silicon

Large linear magnetoresistance (MR) in electron-injected p-type silicon at very low magnetic field is observed experimentally at room temperature. The large linear MR is induced in electron-dominated space-charge transport regime, where the magnetic field modulation of electron-to-hole density ratio controls the MR, as indicated by the magnetic field dependence of Hall coefficient in the silicon device. Contrary to the space-charge-induced MR effect in unipolar silicon device, where the large linear MR is inhomogeneity-induced, our results provide a different insight into the mechanism of large linear MR in non-magnetic semiconductors that is not based on the inhomogeneity model. This approach enables homogeneous semiconductors to exhibit large linear MR at low magnetic fields that until now has only been appearing in semiconductors with strong inhomogeneities.Comment: 23 pages, 4 figures (main text), 6 figures (supplemental material

Characterization of the first true coaxial 18-fold segmented n-type prototype detector for the GERDA project

The first true coaxial 18-fold segmented n-type HPGe prototype detector produced by Canberra-France for the GERDA neutrinoless double beta-decay project was tested both at Canberra-France and at the Max-Planck-Institut fuer Physik in Munich. The main characteristics of the detector are given and measurements concerning detector properties are described. A novel method to establish contacts between the crystal and a Kapton cable is presented.Comment: 21 pages, 16 Figures, to be submitted to NIM

Clouds, shadows, or twilight? Mayfly nymphs recognise the difference

1. We examined the relative changes in light intensity that initiate night-time locomotor activity changes in nymphs of the mayfly, Stenonema modestum (Heptageniidae). Tests were carried out in a laboratory stream to examine the hypothesis that nymphs increase their locomotion in response to the large and sustained reductions in relative light intensity that take place during twilight but not to short-term daytime light fluctuations or a minimum light intensity threshold. Ambient light intensity was reduced over a range of values representative of evening twilight. Light was reduced over the same range of intensities either continuously or in discrete intervals while at the same time nymph activity on unglazed tile substrata was video recorded. 2. Nymphs increased their locomotor activity during darkness in response to large, sustained relative light decreases, but not in response to short-term, interrupted periods of light decrease. Nymphs did not recognise darkness unless an adequate light stimulus, such as large and sustained relative decrease in light intensity, had taken place. 3. We show that nymphs perceive light change over time and respond only after a lengthy period of accumulation of light stimulus. The response is much lengthier than reported for other aquatic organisms and is highly adaptive to heterogeneous stream environments

Not Just for Geeks: A practical approach to linked data for digital collections managers

As digital library managers, we know our collections contain rich metadata, but data (or metadata) are encapsulated in these records and are accessible to users only when records containing them are retrieved in a search. This approach for managing data, although a common practice that extends far beyond digital collections, creates silos of data. Data associated with records is isolated and does not directly link to related data existing in other records. These silos hide valuable relationships among data, leaving to users the task of discovering these hidden connections. Join other digital library managers at this workshop designed to provide you with key concepts to understand Linked Data and a selection of hands-on activities and demonstrations that will show step-by-step exactly how CONTENTdm metadata can be transformed into linked data. The workshop will also provide a forum for us to discuss how Linked Data will impact our guiding principles, best practices, and local workflows. This workshop is geared toward beginners – not just data geeks – and is designed for curious exploration and active learning in a welcoming environment. The Linked Data movement has gained momentum and it is not too early for us to start thinking about how this paradigm shift, akin to the transition from card catalogs to online catalogs, will affect discovery of our collections and our future workflows. How will we contribute our resources to the Linked Data Cloud where digital library data can be created locally and linked to existing data accessible globally? The movement is already being embraced by key organizations in the library field and the resources already exist to help us experiment with transitioning our collections

Linked Data Demystified: Practical Efforts to Transform CONTENTdm Metadata for the Linked Data Cloud

The library literature and events like the ALA Annual Conference have been inundated with presentations and articles on linked data. At UNLV Libraries, we understand the importance of linked data in helping to better service our users. We have designed and initiated a pilot project to apply linked data concepts to the practical task of transforming a sample set of our CONTENTdm digital collections data into future-oriented linked data. This presentation will outline rationale for beginning work in linked data and detail the phases we will undertake in the proof of concept project. We hope through this research experiment to evaluate challenges and benefits of publishing digital collection data into the Linked Data Cloud