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$_2$ plane ($P_{pl}$) and the corresponding hole content per unit volume ($P_{3D}$), 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 ($T_c$) varies systematically with $P_{3D}$ as a superconducting \textquotedblleft $dome$\textquotedblright with a universal optimal hole-doping concentration $P_{3D}^{opt.}$ = 1.6 $\times$ 10$^{21}$ cm$^{-3}$ for single-layer high temperature superconductors. We suggest that $P_{3D}^{opt.}$ determines the upper bound of the electronic energy of underdoped single-layer high-$T_c$ 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 CoS1.9_{1.9}Se0.1_{0.1}

Undoped CoS$_2$ is an isotropic itinerant ferromagnet with a continuous or nearly continuous phase transition at $T_{\rm C} = 122$ K. In the doped CoS$_{1.9}$Se$_{0.1}$ system, the Curie temperature is lowered to $T_{\rm C} = 90$ 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 ($< 0.04$ meV), indicating that this system is also an excellent isotropic (soft) ferromagnet. In a wide temperature range up to $0.9T_{\rm C}$, the spin-wave stiffness $D(T)$ follows the prediction of the two-magnon interaction theory, $D(T) = D(0)(1 - AT^{5/2})$, with $D(0) = 131.7 \pm 2.8$ meV-\AA$^{2}$. The stiffness, however, does not collapse as $T \to T_{\rm C}$ 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$_3$.Comment: 8pages, 8figure

Quantum Oscillations in Cux_xBi2_2Se3_3 in High Magnetic Fields

Cu$_x$Bi$_2$Se$_3$ 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 Cu$_x$Bi$_2$Se$_3$ 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 Cu$_x$Bi$_2$Se$_3$.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 T$_N\sim$22K with propagation vector \textbf{k}=(0,0,$\sim$0.18). On cooling below T$_N$, the propagation vector increases and saturates at the commensurate value \textbf{k}=(0,0,0.25). The magnetic structure below T$_N$ 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$_4$), 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