Superconductivity in epitaxial thin films of NaxCoO2 y D2O

The observation of superconductivity in the layered transition metal oxide NaxCoO2 y H2O (K. Takada et al., Nature 422, 53 (2003)) has caused a tremendous upsurge of scientific interest due to its similarities and its differences to the copper based high-temperature superconductors. Two years after the discovery, we report the fabrication of single-phase superconducting epitaxial thin films of Na0.3CoO2 x 1.3 D2O grown by pulsed laser deposition technique. This opens additional roads for experimental research exploring the superconducting state and the phase diagram of this unconventional material.Comment: 3 pages, 5 figure

The Ursinus Weekly, May 31, 1915

Annual exercises of commencement week • Varsity victorious in two contests • Dr. Good delivers excellent lecture • Senior picnic • Brotherhood of St. Paul banquets • Inter-class baseball game • To prospective students • Literary societies • Pritchard resigns managership • 1913 class meetinghttps://digitalcommons.ursinus.edu/weekly/2667/thumbnail.jp

Frustration-induced quantum criticality in Ni-doped CePdAl as revealed by the μSR technique

In CePdAl, the 4⁢f moments of cerium arrange to form a geometrically frustrated kagome lattice. Due to frustration, in addition to Kondo and Ruderman-Kittel-Kasuya-Yosida interactions, this metallic system shows a long-range magnetic order (LRO) with a TN of only 2.7 K. Upon Ni doping at the Pd sites, TN is further suppressed, to reach zero at a critical concentration xc≈0.15. Here, by using muon-spin relaxation and rotation (µ⁢SR), we investigate CePd1−xNix⁢Al at a local level for five different Ni concentrations, both above and below xc. Like the parent CePdAl compound, for x=0.05, we observe an incommensurate LRO, which turns into a quasistatic magnetic order for x=0.1 and 0.14. More interestingly, away from xc, for x=0.16 and 0.18, we still observe a non-Fermi-liquid (NFL) regime, evidenced by a power-law divergence of the longitudinal relaxation at low temperatures. In this case, longitudinal field measurements exhibit a time-field scaling, indicative of cooperative spin dynamics that persists for x>xc. Furthermore, like the externally applied pressure, the chemical pressure induced by Ni doping suppresses the region below T*, characterized by a spin-liquid-like dynamical behavior. Our results suggest that the magnetic properties of CePdAl are similarly affected by the hydrostatic and the chemical pressure. We also confirm that the unusual NFL regime (compared with conventional quantum critical systems) is due to the presence of frustration that persists up to the highest Ni concentrations

Frustration-induced quantum criticality in Ni-doped CePdAl as revealed by the μ\muSR technique

In CePdAl, the 4$f$ moments of cerium arrange to form a geometrically frustrated kagome lattice. Due to frustration, in addition to Kondo- and Ruderman-Kittel-Kasuya-Yosida interactions, this metallic system shows a long-range magnetic order (LRO) with a $T_{\rm N}$ of only 2.7\,K. Upon Ni doping at the Pd sites, $T_{\rm N}$ is further suppressed, to reach zero at a critical concentration $x_c \approx 0.15$. Here, by using muon-spin relaxation and rotation ($\mu$SR), we investigate CePd${1-x}$Ni$_x$Al at a local level for five different Ni-concentrations, both above and below $x_c$. Like the parent CePdAl compound, for $x = 0.05$, we observe an incommensurate LRO, which turns into a quasi-static magnetic order for $x = 0.1$ and 0.14. More interestingly, away from $x_c$, for $x = 0.16$ and 0.18, we still observe a non-Fermi liquid regime, evidenced by a power-law divergence of the longitudinal relaxation at low temperatures. In this case, longitudinal field measurements exhibit a time-field scaling, indicative of a cooperative spin dynamics that persists for $x > x_c$. Furthermore, like the externally applied pressure, the chemical pressure induced by Ni doping suppresses the region below $T^*$, characterized by a spin-liquid like dynamical behavior. Our results suggest that the magnetic properties of CePdAl are similarly affected by the hydrostatic- and the chemical pressure. We also confirm that the unusual non-Fermi liquid regime (compared with conventional quantum critical systems) is due to the presence of frustration that persists up to the highest Ni concentrations.Comment: 8 pages, 6 figure

Dynamic instability of 3D stationary and traveling planar dark solitons

Here we revisit the topic of stationary and propagating solitonic excitations in self-repulsive three-dimensional (3D) Bose–Einstein condensates by quantitatively comparing theoretical analysis and associated numerical computations with our experimental results. Motivated by numerous experimental efforts, including our own herein, we use fully 3D numerical simulations to explore the existence, stability, and evolution dynamics of planar dark solitons. This also allows us to examine their instability-induced decay products including solitonic vortices and vortex rings. In the trapped case and with no adjustable parameters, our numerical findings are in correspondence with experimentally observed coherent structures. Without a longitudinal trap, we identify numerically exact traveling solutions and quantify how their transverse destabilization threshold changes as a function of the solitary wave speed

Investigation of the thermal expansion and heat capacity of the CaCu3Ti4O12 ceramics

The thermal expansion of the CaCu3Ti4O12 ceramics has been measured over a wide temperature range 120–1200 K. The high quality of the samples under study has been confirmed by good agreement of the results of measurements of the heat capacity in the range 2–300 K and in the vicinity of the phase transition of magnetic nature at 25 K with the data for the single crystal. No anomalies in the thermal expansion that can be associated with the phase transition at 726–732 K assumed by other investigators have been found. The influence exerted on the thermal expansion by the heat treatment of the sample in a helium atmosphere and in air has been investigated

The Ca2+ sensor protein Swiprosin-1/EFhd2 is present in neurites and involved in kinesin-mediated transport in neurons

This work was supported by grants from the German Science Foundation (Deutsche Forschungsgemeinschaft, DFG; FOR832, to DM), the German Federal Ministry of Education and Research (01GQ113; to BW), the Bavarian Ministry of Sciences, Research and the Arts in the framework of the Bavarian Molecular Biosystems Reseach Network, the Interdisciplinary Center for Clinical Research (IZKF, Universitatsklinikum Erlangen; E8, to DM; NIII, to BW; Lab rotation to MR), the ELAN Fonds (Universitatsklinikum Erlangen; 11.08.19.1, to IP), and the Alzheimer’s Research UK (EB, FGM).Swiprosin-1/EFhd2 (EFhd2) is a cytoskeletal Ca2+ sensor protein strongly expressed in the brain. It has been shown to interact with mutant tau, which can promote neurodegeneration, but nothing is known about the physiological function of EFhd2 in the nervous system. To elucidate this question, we analyzed EFhd2-/-/lacZ reporter mice and showed that lacZ was strongly expressed in the cortex, the dentate gyrus, the CA1 and CA2 regions of the hippocampus, the thalamus, and the olfactory bulb. Immunohistochemistry and western blotting confirmed this pattern and revealed expression of EFhd2 during neuronal maturation. In cortical neurons, EFhd2 was detected in neurites marked by MAP2 and co-localized with preand post-synaptic markers. Approximately one third of EFhd2 associated with a biochemically isolated synaptosome preparation. There, EFhd2 was mostly confined to the cytosolic and plasma membrane fractions. Both synaptic endocytosis and exocytosis in primary hippocampal EFhd2-/- neurons were unaltered but transport of synaptophysin-GFP containing vesicles was enhanced in EFhd2-/- primary hippocampal neurons, and notably, EFhd2 inhibited kinesin mediated microtubule gliding. Therefore, we found that EFhd2 is a neuronal protein that interferes with kinesin-mediated transport.Peer reviewe

Evidence for Jahn-Teller distortions at the antiferromagnetic transition in LaTiO3_3

LaTiO$_3$ is known as Mott-insulator which orders antiferromagnetically at $T_{\rm N}=146$ K. We report on results of thermal expansion and temperature dependent x-ray diffraction together with measurements of the heat capacity, electrical transport measurements, and optical spectroscopy in untwinned single crystals. At $T_{\rm N}$ significant structural changes appear, which are volume conserving. Concomitant anomalies are also observed in the dc-resistivity, in bulk modulus, and optical reflectivity spectra. We interpret these experimental observations as evidence of orbital order.Comment: 4 pages, 4 figures; published in Phys. Rev. Lett. 91, 066403 (2003