1,208 research outputs found
Universal optimal hole-doping concentration in single-layer high-temperature cuprate superconductors
We argue that in cuprate physics there are two types, hole content per
CuO plane () and the corresponding hole content per unit volume
(), of hole-doping concentrations for addressing physical properties
that are two-dimensional (2D) and three-dimensional (3D) in nature,
respectively. We find that superconducting transition temperature ()
varies systematically with as a superconducting \textquotedblleft
\textquotedblright with a universal optimal hole-doping concentration
= 1.6 10 cm for single-layer high
temperature superconductors. We suggest that determines the
upper bound of the electronic energy of underdoped single-layer high-
cuprates.Comment: 8 pages, 4 figures; added references ;accepted for the publication in
Supercond. Sci. Technol ; Ref. 13 is revise
First-order transition in the itinerant ferromagnet CoSSe
Undoped CoS is an isotropic itinerant ferromagnet with a continuous or
nearly continuous phase transition at K. In the doped
CoSSe system, the Curie temperature is lowered to K, and the transition becomes clearly first order in nature. In particular
we find a discontinuous evolution of the spin dynamics as well as strong time
relaxation in the ferromagnetic Bragg intensity and small angle neutron
scattering in vicinity of the ferromagnetic transition. In the ordered state
the long-wavelength spin excitations were found to be conventional
ferromagnetic spin-waves with negligible spin-wave gap ( meV),
indicating that this system is also an excellent isotropic (soft) ferromagnet.
In a wide temperature range up to , the spin-wave stiffness
follows the prediction of the two-magnon interaction theory, , with meV-\AA. The stiffness,
however, does not collapse as from below. Instead a
quasielastic central peak abruptly develops in the excitation spectrum, quite
similar to results found in the colossal magnetoresistance oxides such as
(La-Ca)MnO.Comment: 8pages, 8figure
Quantum Oscillations in CuBiSe in High Magnetic Fields
CuBiSe has drawn much attention as the leading candidate to be
the first topological superconductor and the realization of coveted Majorana
particles in a condensed matter system. However, there has been increasing
controversy about the nature of its superconducting phase. This study sheds
light on present ambiguity in the normal state electronic state, by providing a
complete look at the quantum oscillations in magnetization in
CuBiSe at intense high fields up to 31T. Our study focuses on the
angular dependence of the quantum oscillation pattern in a low carrier
concentration. As magnetic field tilts from along the crystalline c-axis to
ab-plane, the change of the oscillation period follows the prediction of the
ellipsoidal Fermi surface. As the doping level changes, the 3D Fermi surface is
found to transform into quasi-cylindrical at high carrier density. Such a
transition is potentially a Lifshitz transition of the electronic state in
CuBiSe.Comment: 6 pages, 6 figures, submitted to Phys. Rev.
Non-collinear long-range magnetic ordering in HgCr2S4
The low-temperature magnetic structure of \HG has been studied by
high-resolution powder neutron diffraction. Long-range incommensurate magnetic
order sets in at T22K with propagation vector
\textbf{k}=(0,0,0.18). On cooling below T, the propagation vector
increases and saturates at the commensurate value \textbf{k}=(0,0,0.25). The
magnetic structure below T consists of ferromagnetic layers in the
\textit{ab}-plane stacked in a spiral arrangement along the \textit{c}-axis.
Symmetry analysis using corepresentations theory reveals a point group symmetry
in the ordered magnetic phase of 422 (D), which is incompatible with
macroscopic ferroelectricity. This finding indicates that the spontaneous
electric polarization observed experimentally cannot be coupled to the magnetic
order parameter
HeMIS: Hetero-Modal Image Segmentation
We introduce a deep learning image segmentation framework that is extremely
robust to missing imaging modalities. Instead of attempting to impute or
synthesize missing data, the proposed approach learns, for each modality, an
embedding of the input image into a single latent vector space for which
arithmetic operations (such as taking the mean) are well defined. Points in
that space, which are averaged over modalities available at inference time, can
then be further processed to yield the desired segmentation. As such, any
combinatorial subset of available modalities can be provided as input, without
having to learn a combinatorial number of imputation models. Evaluated on two
neurological MRI datasets (brain tumors and MS lesions), the approach yields
state-of-the-art segmentation results when provided with all modalities;
moreover, its performance degrades remarkably gracefully when modalities are
removed, significantly more so than alternative mean-filling or other synthesis
approaches.Comment: Accepted as an oral presentation at MICCAI 201
Experimental study on damage pattern caused on Malaysian made hollow blocks by guns of different calibers
Firearm and ballistics in an important area in forensic investigation. Among three ballistics, terminal ballistics plays a vital
role in to solve the mystery in crime scenes. The present experimental study is aimed to study the damage pattern caused on
Malaysian made hollow blocks by using various firearm. For the experimental study, firearms viz. 0.38 revolver, 9mm submachine
gun, 9 mm semi auto pistol, 5.56 mm rifle and 7.62 mm rifle were used with varying ranges. The shooting experiment
was conducted at Sungai Buloh shooting range by trained firearms experts, Polis Di Raja Malaysia, Bukit Aman. Kuala
Lumpur. The entry and exit damages were analyzed and the result of the investigation provided promising result in determining
the type of firearm and other useful information. The entry damages are found to be comparatively smaller than the exit
damages in the hollow blocks. The long arms caused more damages on the hollow blocks comparatively than hand arms
A Universal Intrinsic Scale of Hole Concentration for High-Tc Cuprates
We have measured thermoelectric power (TEP) as a function of hole
concentration per CuO2 layer, Ppl, in Y1-xCaxBa2Cu3O6 (Ppl = x/2) with no
oxygen in the Cu-O chain layer. The room-temperature TEP as a function of Ppl,
S290(Ppl), of Y1-xCaxBa2Cu3O6 behaves identically to that of La2-zSrzCuO4 (Ppl
= z). We argue that S290(Ppl) represents a measure of the intrinsic equilibrium
electronic states of doped holes and, therefore, can be used as a common scale
for the carrier concentrations of layered cuprates. We shows that the Ppl
determined by this new universal scale is consistent with both hole
concentration microscopically determined by NQR and the hole concentration
macroscopically determined by the Cu valency. We find two characteristic
scaling temperatures, TS* and TS2*, in the TEP vs. temperature curves that
change systematically with doping. Based on the universal scale, we uncover a
universal phase diagram in which almost all the experimentally determined
pseudogap temperatures as a function of Ppl fall on two common curves; upper
pseudogap temperature defined by the TS* versus Ppl curve and lower pseudogap
temperature defined by the TS2* versus Ppl curve. We find that while pseudogaps
are intrinsic properties of doped holes of a single CuO2 layer for all high-Tc
cuprates, Tc depends on the number of layers, therefore the inter-layer
coupling, in each individual system.Comment: 11 pages, 9 figures, accepted for publication in Physical Review
Chemically Induced Ferromagnetism Near Room Temperature in Single Crystal (Zn1−xCrx)Te Half-Metal
Magnetic Semiconductors Are at the Core of Recent Spintronics Research Endeavors. Chemically Doped II-VI Diluted Magnetic Semiconductors, such as (Zn1−xCrx)Te, Provide a Promising Platform in This Quest. However, a Detailed Knowledge of the Microscopic Nature of Magnetic Ground State is Necessary for Any Practical Application. Here, We Report on the Synergistic Study of (Zn1−xCrx)Te Single Crystals using Elastic Neutron Scattering Measurements and Density Functional Calculations. for the First Time, Our Research Unveils the Intrinsic Properties of Ferromagnetic State in a Macroscopic Specimen of (Zn0.8Cr0.2)Te. the Ferromagnetism is Onset at TC ∼ 290 K and Remains Somewhat Independent to Modest Change in the Substitution Coefficient X. We Show that Magnetic Moments on Zn/Cr Sites Develop Ferromagnetic Correlation in the A-C Plane with a Large Ordered Moment of Μ = 3.08 ΜB. Magnetic Moment Across the Lattice is Induced Via the Mediation of Te Sites, Uncoupled to the Number of Dopant Carriers as Inferred from the Density Functional Calculation. Additionally, the Ab Initio Calculations Also Reveal Half-Metallicity in X = 0.2 Composition. These Properties Are Highly Desirable for Future Spintronic Applications
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