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4. Vortex Dynamics and Phase Diagram in the Electron Doped Cuprate Superconductor Pr$_{0.87}$LaCe$_{0.13}$CuO$_4$

Author

Salem-Sugui Jr., S., Lopes, P. V., Kern, M. P., Sundar, Shyam, Liu, Zhaoyu, Li, Shiliang, Luo, Huiqian, and Ghivelder, L.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

Second magnetization peak (SMP) in hole-doped cuprates and iron pnictide superconductors has been widely explored. However, similar feature in the family of electron-doped cuprates is not common. Here, we report the vortex dynamics study in the single crystal of an electron-doped cuprate Pr$_{0.87}$LaCe$_{0.13}$CuO$_4$ superconductor using dc magnetization measurements. A SMP feature in the isothermal $M(H)$ was observed for $H$$\parallel$$ab$-planes. On the other hand, no such feature was observed for $H$$\parallel$$c$-axis in the crystal. Using magnetic relaxation data, a detailed analysis of activation pinning energy via collective creep theory suggests an elastic to plastic creep crossover across the SMP. Moreover, for $H$$\parallel$$ab$, a peak in the temperature dependence of critical current density is also observed near 7 K, which is likely be related to a dimensional crossover (3D-2D) associated to the emergence of Josephson vortices at low temperatures. The anisotropy parameter obtained $\gamma$ $\approx$ 8-11 indicates the 3D nature of vortex lattice mainly for $H$$\parallel$$c$-axis. The $H$-$T$ phase diagrams for $H$$\parallel$$c$ and $H$$\parallel$$ab$ are presented., Comment: 10 Pages, 8 Figures

Published
2020
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7. Optical Cryocooling of Diamond

Author

Kern, M., Jeske, J., Lau, D. M. W., Greentree, A. D., Jelezko, F., and Twamley, J.

Subjects
Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Optics
Abstract

The cooling of solids by optical means only using anti-Stokes emission has a long history of research and achievements. Such cooling methods have many advantages ranging from no-moving parts or fluids through to operation in vacuum and may have applications to cryosurgery. However achieving large optical cryocooling powers has been difficult to achieve except in certain rare-earth crystals. Through study of the emission and absorption cross sections we find that diamond, containing either NV or SiV (Nitrogen or Silicon vacancy), defects shows potential for optical cryocooling and in particular, NV doping shows promise for optical refrigeration. We study the optical cooling of doped diamond microcrystals ranging 10-250 microns in diameter trapped either in vacuum or in water. For the vacuum case we find NV-doped microdiamond optical cooling below room temperature could exceed 10 Kelvin, for irradiation powers of P< 100 mW. We predict that such temperature changes should be easily observed via large alterations in the diffusion constant for optically cryocooled microdiamonds trapped in water in an optical tweezer or via spectroscopic signatures such as the ZPL width or Raman line., Comment: 8 pages, 6 figures

Published
2017
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8. How are we measuring resilience in children? A systematic review

Author

Hall, JR, Deery, B, Sciberras, E, Kern, M, Quach, J, Hall, JR, Deery, B, Sciberras, E, Kern, M, and Quach, J

Abstract

Resilience in children has received considerable interest from research bodies, policymakers, practitioners, and education bodies due to its potential impact on well-being, as well as physical and mental health. To support and cultivate resilience, appropriate measurement is important. However, numerous definitions and measures of resilience exist. To provide clarity, this paper offers a systematic review of measures used to assess resilience in children. Systematic search conducted in Medline, ERIC, ProQuest Central, Scopus, PsychINFO, and Web of Science. Keywords included ‘resilien* and measure* and child*’. Eligible studies: assessed children aged 0–12 years, of all abilities; and, contained a measure to assess resilience, inclusive of parent, teacher, and/or child-report measures. From 24,902 studies retrieved, 86 studies were included, identifying 54 measures for assessing resilience. 28 measures identified as proposing to measure resilience construct as their primary goal, whilst 27 were identified as proxy measures assessing constructs relating to resilience. Overall, 34 % of articles reported on both reliability and validity, with 20 % reporting neither of these. While there is a range of measures used to assess resilience in children, there is a lack of consensus regarding what constructs and domains represent resilience. A large proportion had minimal or no psychometrics reported, highlighting the limitations of this area. This is an important starting point for consolidating how resilience is defined and measured within research.

Published
2024

45. Strategic Resource Planning

Author

Owusu, Gilbert, Anim-Ansah, G., Kern, M., Dorne, Raphael, Voudouris, Christos, editor, Lesaint, David, editor, and Owusu, Gilbert, editor

Published
2008
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