230 research outputs found
Inhomogeneous magnetism in single crystalline SrCuIrO: Implications to phase-separation concepts
The single crystalline form of an insulator, SrCuIrO, is
shown to exhibit unexpectedly more than one magnetic transition (at 5 and 19 K)
with spin-glass-like magnetic susceptibility behaviour. On the basis of this
finding, viz., inhomogeneous magnetism in a chemically homogeneous material, we
propose that the idea of "phase- separation" described for manganites [1] is
more widespread in different ways. The observed experimental features enable us
to make a comparison with the predictions of a recent toy model [2] on {\it
magnetic} phase separation in an insulating environment.Comment: 4 pages, 4 figure
Magnetic excitations of Fe_{1+y}Se_xTe_{1-x} in magnetic and superconductive phases
We have used inelastic neutron scattering and muon-spin rotation to compare
the low energy magnetic excitations in single crystals of superconducting
Fe1.01Se0.50Te0.50 and non-superconducting Fe1.10Se0.25Te0.75. We confirm the
existence of a spin resonance in the superconducting phase of
Fe1.01Se0.50Te0.50, at an energy of 7 meV and a wavevector of (1/2,1/2,0). The
non-superconducting sample exhibits two incommensurate magnetic excitations at
(1/2,1/2,0)\pm(0.18,-0.18,0) which rise steeply in energy, but no resonance is
observed at low energies. A strongly dispersive low-energy magnetic excitation
is also observed in Fe1.10Se0.25Te0.75 close to the commensurate
antiferromagnetic ordering wavevector (1/2-\delta,0,1/2) where \delta \approx
0.03. The magnetic correlations in both samples are found to be quasi-two
dimensional in character and persist well above the magnetic
(Fe1.10Se0.25Te0.75) and superconducting (Fe1.01Se0.50Te0.50) transition
temperatures.Comment: 10 pages, 4 figure
Single molecule trapping and sensing using dual nanopores separated by a zeptoliter nanobridge
There is a growing realization, especially within the diagnostic and therapeutic community, that the amount of information enclosed in a single molecule can not only enable a better understanding of biophysical pathways, but also offer exceptional value for early stage biomarker detection of disease onset. To this end, numerous single molecule strategies have been proposed, and in terms of label-free routes, nanopore sensing has emerged as one of the most promising methods. However, being able to finely control molecular transport in terms of transport rate, resolution, and signal-to-noise ratio (SNR) is essential to take full advantage of the technology benefits. Here we propose a novel solution to these challenges based on a method that allows biomolecules to be individually confined into a zeptoliter nanoscale droplet bridging two adjacent nanopores (nanobridge) with a 20 nm separation. Molecules that undergo confinement in the nanobridge are slowed down by up to 3 orders of magnitude compared to conventional nanopores. This leads to a dramatic improvement in the SNR, resolution, sensitivity, and limit of detection. The strategy implemented is universal and as highlighted in this manuscript can be used for the detection of dsDNA, RNA, ssDNA, and proteins
Interplay between superconductivity and magnetism in K-doped EuFe2As2
Superconductivity is found in 50% K-doped EuFe2As2 sample below 33 K. Our
results of electrical resistivity, magnetic susceptibility and 57Fe and 151Eu
Mossbauer spectroscopy provide clear evidence that the ordering of the Fe
moments observed at 190 K in undoped EuFe2As2 is completely suppressed in our
50% K doped sample, thus there is no coexistence between the Fe magnetic order
and the superconducting state. However, short range ordering of the Eu moments
is coexisting with the superconducting state below 15 K. A bump in the
susceptibility well below Tc as well as a slight broadening of the Fe Mossbauer
line below 15 K evidence an interplay between the Eu magnetism and the
superconducting state.Comment: 7 pages, 6 figure
Upper critical field, lower critical field and critical current density of FeTe0.60Se0.40 single crystal
The transport and magnetic studies are performed on high quality
FeTe0.60Se0.40 single crystals to determine the upper critical fields (Hc2),
lower critical field (Hc1) and the Critical current density (Jc). The value of
upper critical field Hc2 are very large, whereas the activation energy as
determined from the slope of the Arrhenius plots are was found to be lower than
that in the FeAs122 superconductor. The lower critical field was determined in
ab direction and c direction of the crystal, and was found to have a anisotropy
of 'gamma'{=(Hc1//c) / (Hc1//b)} ~ 4. The magnetic isotherms measured up to 12
Tesla shows the presence of fishtail behavior. The critical current densities
at 1.8K of the single crystal was found to almost same in both ab and c
direction as 1X105 Amp/cm2 in low field regime.Comment: 9 pages, 6 figure
Fabrication and characterization of dual function nanoscale pH-scanning ion conductance microscopy (SICM) probes for high resolution pH mapping
The easy fabrication and use of nanoscale dual function pH-scanning ion conductance microscopy (SICM) probes is reported. These probes incorporate an iridium oxide coated carbon electrode for pH measurement and an SICM barrel for distance control, enabling simultaneous pH and topography mapping. These pH-SICM probes were fabricated rapidly from laser pulled theta quartz pipets, with the pH electrode prepared by in situ carbon filling of one of the barrels by the pyrolytic decomposition of butane, followed by electrodeposition of a thin layer of hydrous iridium oxide. The other barrel was filled with an electrolyte solution and Ag/AgCl electrode as part of a conductance cell for SICM. The fabricated probes, with pH and SICM sensing elements typically on the 100 nm scale, were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and various electrochemical measurements. They showed a linear super-Nernstian pH response over a range of pH (pH 2–10). The capability of the pH-SICM probe was demonstrated by detecting both pH and topographical changes during the dissolution of a calcite microcrystal in aqueous solution. This system illustrates the quantitative nature of pH-SICM imaging, because the dissolution process changes the crystal height and interfacial pH (compared to bulk), and each is sensitive to the rate. Both measurements reveal similar dissolution rates, which are in agreement with previously reported literature values measured by classical bulk methods
Microstructural magnetic phases in superconducting FeTe0.65Se0.35
In this paper, we address a number of outstanding issues concerning the
nature and the role of magnetic inhomogenities in the iron chalcogenide system
FeTe1-xSex and their correlation with superconductivity in this system. We
report morphology of superconducting single crystals of FeTe0.65Se0.35 studied
with transmission electron microscopy, high angle annular dark field scanning
transmission electron microscopy and their magnetic and superconducting
properties characterized with magnetization, specific heat and magnetic
resonance spectroscopy. Our data demonstrate a presence of nanometre scale
hexagonal regions coexisting with tetragonal host lattice, a chemical disorder
demonstrating non homogeneous distribution of host atoms in the crystal
lattice, as well as hundreds-of-nanometres-long iron-deficient bands. From
magnetic data and ferromagnetic resonance temperature dependence, we attribute
magnetic phases in Fe-Te-Se to Fe3O4 inclusions and to hexagonal symmetry
nanometre scale regions with structure of Fe7Se8 type. Our results suggest that
nonhomogeneous distribution of host atoms might be an intrinsic feature of
superconducting Fe-Te-Se chalcogenides and we find a surprising correlation
indicating that faster grown crystal of inferior crystallographic properties is
a better superconductor.Comment: 16 pages, 8 figures, 2 table
Non-steroidal anti-inflammatory drug induced acute kidney injury in the community dwelling general population and people with chronic kidney disease:Systematic review and meta-analysis
Complete search strategy. The complete search strategy for the systematic review for both Medline and Embase. (DOCX 22 kb
A review of Fe-chalcogenide superconductors: the simplest Fe-based superconductor
Here we summarize the physical properties of the newly discovered
Fe-chalcogenide superconductors. The Fe-chalcogenide superconductors attract us
as the simplest Fe-based superconductors. Furthermore, Fe chalcogenides show a
huge pressure effect on their superconducting properties. The origin of the
high transition temperature was discussed with both the change in crystal
structure and magnetism. The progress on the thin-film and superconducting-wire
fabrications are also described.Comment: A review article of Fe-chalcogenide superconductor submitted to J.
Phys. Soc. Jpn. 51 pages, 54 figures including reprinted from the published
paper
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