52 research outputs found
Pressure Evolution of Magnetism in URhGa
In this paper, we report the results of an ambient and high pressure study of
a 5f-electron ferromagnet URhGa. The work is focused on measurements of
magnetic and thermodynamic properties of a single crystal sample and on the
construction of the p-T phase diagram. Diamond anvil cells were employed to
measure the magnetization and electrical resistivity pressures up to ~ 9 GPa.
At ambient pressure, URhGa exhibits collinear ferromagnetic ordering of uranium
magnetic moments {\mu}U ~ 1.1 {\mu}B (at 2 K) aligned along the c-axis of the
hexagonal crystal structure below the Curie temperature TC = 41K. With the
application of pressure up to 5GPa the ordering temperature TC initially
increases whereas the saturated moment slightly decreases. The rather
unexpected evolution is put in the context of the UTX family of compounds.Comment: arXiv admin note: text overlap with arXiv:1611.0327
Bonding trends within ternary Isocoordinate chalcogenide glasses GeAsSe
A structural study is presented of ab-initio molecular dynamics simulations
of Ge-As-Se calcogenide glasses performed at the same mean coordination number
but differing stoichiometry ranging between Se rich and Se poor glasses.
Starting configurations are generated via Reverse Monte Carlo (RMC) simulations
of Extended X-ray Absorption Fine Structure (EXAFS) measurements of
experimental samples. Structural analysis is presented illustrating the bonding
trends found with changing stoichiometry.Comment: 26 pages, 9 figures. Submitted to Physical Review
Chiminey: Reliable Computing and Data Management Platform in the Cloud
The enabling of scientific experiments that are embarrassingly parallel, long
running and data-intensive into a cloud-based execution environment is a
desirable, though complex undertaking for many researchers. The management of
such virtual environments is cumbersome and not necessarily within the core
skill set for scientists and engineers. We present here Chiminey, a software
platform that enables researchers to (i) run applications on both traditional
high-performance computing and cloud-based computing infrastructures, (ii)
handle failure during execution, (iii) curate and visualise execution outputs,
(iv) share such data with collaborators or the public, and (v) search for
publicly available data.Comment: Preprint, ICSE 201
Anisotropic Enhancement of Lower Critical Field in Ultraclean Crystals of Spin-Triplet Superconductor UTe2
The paramagnetic spin-triplet superconductor UTe has attracted
significant attention because of its exotic superconducting properties
including an extremely high upper critical field and possible chiral
superconducting states. Recently, ultraclean single crystals of UTe have
become available, and thus measurements on these crystals are crucial to
elucidate the intrinsic superconducting properties. Here, we report the
thermodynamic critical field , the lower critical field , and the upper critical field at low fields of these
high-quality single crystals. From the comparison of the anisotropies in
and , we find that the experimental
values with the magnetic field along - and -axes are anomalously
enhanced, showing unusual low-temperature upturns. We propose an effect of the
strong Ising-like ferromagnetic fluctuations on the vortex line energy as the
origin of the anisotropic enhancement of .Comment: 7 pages, 6 figure
Anomalous vortex dynamics in spin-triplet superconductor UTe
The vortex dynamics in the spin-triplet superconductor, UTe, are studied
by measuring the DC electrical resistivity with currents along the -axis
under magnetic fields along the -axis. Surprisingly, we have discovered an
island region of low critical current deep inside the superconducting (SC)
state, well below the SC upper critical field, attributed to a weakening of
vortex pinning. Notably, this region coincides with the recently proposed
intermediate-field SC state. We discuss the possibility of nonsingular vortices
in the intermediate state, where SC order parameter does not vanish entirely in
the vortex cores due to the mixing of multiple SC components
Pressure-induced huge increase of Curie temperature of the van der Waals ferromagnet VI3
Evolution of magnetism in single crystals of the van der Waals compound VI3
in external pressure up to 7.3 GPa studied by measuring magnetization and ac
magnetic susceptibility is reported. Four magnetic phase transitions, at T1 =
54.5 K, T2 = 53 K, TC = 49.5 K, and TFM = 26 K, respectively have been observed
at ambient pressure. The first two have been attributed to the onset of
ferromagnetism in specific crystal-surface layers. The bulk ferromagnetism is
characterized by the magnetic ordering transition at Curie temperature TC and
the transition between two different ferromagnetic phases TFM, accompanied by a
structure transition from monoclinic to triclinic symmetry upon cooling. The
pressure effects on magnetic parameters were studied with three independent
techniques. TC was found to be almost unaffected by pressures up to 0.6 GPa
whereas TFM increases rapidly with increasing pressure and reaches TC at a
triple point at ~ 0.85 GPa. At higher pressures, only one magnetic phase
transition is observed moving to higher temperatures with increasing pressure
to reach 99 K at 7.3 GPa. In contrast, the low-temperature bulk magnetization
is dramatically reduced by applying pressure (by more than 50% at 2.5 GPa)
suggesting a possible pressure-induced reduction of vanadium magnetic moment.
We discussed these results in light of recent theoretical studies to analyze
exchange interactions and provide how to increase the Curie temperature of VI3.Comment: 20 pages, 16 figure
From Cadomian arc to Ordovician passive margin: geochemical records preserved in metasedimentary successions of the Orlica-Śnieżnik Dome in SW Poland
Investigation of bonding within ab initio models of GeAsSe glasses
A study is presented into the structural details of ab initio molecular dynamics simulations of GeAsSe chalcogenide glasses with ideal stoichiometry over a range of mean coordination numbers (MCN). The structural variability dependence upon initial start
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