Search results for "POLARIZATION"
showing 10 items of 1884 documents
Photoinduced magnetization wave in diluted magnetic semiconductors
2006
We derive an evolutional equation incorporating the processes of spin-polarization transfer from an electron to a magnetic ion subsystem of a diluted magnetic semiconductor along with spin-lattice relaxation and spatial spin diffusion. Above equation has been obtained for nonequilibrium magnetization due to exchange scattering of photoexcited charge carriers by magnetic ions. We show that the mechanism of a band gap narrowing due to exchange scattering requires relatively low optical power to reach an optical bistability for pump frequency range close to crystal band gap. In a bulk crystal, only relatively small local area with essential magnetization enhancement can absorb optical power, t…
Optical magnetic circular dichroism in threshold photoemission from a magnetite thin film
2011
Threshold photoemission excited by polarization-modulated ultraviolet femtosecond laser light is exploited for phase-sensitive detection of magnetic circular dichroism (MCD) for a magnetite thin film. Magnetite (Fe(3)O(4)) shows a magnetic circular dichroism of ∼(4.5 ± 0.3) × 10(-3) for perpendicularly incident circularly polarized light and a magnetization vector switched parallel and antiparallel to the helicity vector by an external magnetic field. The asymmetry in threshold photoemission is discussed in comparison to the magneto-optical Kerr effect. The optical MCD contrast in threshold photoemission will provide a basis for future laboratory photoemission studies on magnetic surfaces.
Magnetic state control via field-angle-selective switching in asymmetric rings
2020
Switching the chirality of the vortex state in asymmetric ferromagnetic rings is interesting for multistate memory devices, logic elements, and stray-field-based rotation sensors. This study shows that different magnetic states can be configured by carefully tuning the magnetic field angle. Using time-resolved scanning electron microscopy with polarization analysis to image the magnetization dynamics of these rings, the authors detect competing switching pathways for certain field angles. These different pathways do not change the resulting magnetic states, though, which is advantageous for engineering reliable devices for a range of potential spintronic applications.
Spin orbit torque switching in Ta/CoFeB/MgO without longitudinal fields
2015
Intense investigations are carried out on novel magnetic materials systems with perpendicular magnetic anisotropy (PMA), where new spin-orbit effects occur due to structural inversion asymmetry (SIA). So called spin-orbit torques (SOTs), have been observed for the first time in PMA nano-structures with SIA, when an electric current is injected [1-3], leading to ultra-efficient current-induced domain wall motion and current-induced magnetization switching [2,3].
Real Time Nuclear Magnetic Resonance Detection of Fumarase Activity using Parahydrogen-Hyperpolarized [1-13C]fumarate
2019
Hyperpolarized fumarate can be used as a probe of real-time metabolism in vivo, using carbon-13 magnetic resonance imaging. Dissolution dynamic nuclear polarization is commonly used to produce hyperpolarized fumarate, but a cheaper and faster alternative is to produce hyperpolarized fumarate via PHIP (parahydrogen induced polarization). In this work we trans-hydrogenate [1-13C]acetylene dicarboxylate with para-enriched hydrogen using a commercially available Ru catalyst in water to produce hyperpolarized [1-13C]fumarate. We show that fumarate is produced in 89% yield, with succinate as a side product in 11% yield. The proton polarization is converted into 13C magnetization using a constant …
Total and linearly polarized synchrotron emission from overpressured magnetized relativistic jets
2018
We present relativistic magnetohydrodynamic (RMHD) simulations of stationary overpressured magnetized relativistic jets, which are characterized by their dominant type of energy: internal, kinetic, or magnetic. Each model is threaded by a helical magnetic field with a pitch angle of 45° and features a series of recollimation shocks produced by the initial pressure mismatch, whose strength and number varies as a function of the dominant type of energy. We perform a study of the polarization signatures from these models by integrating the radiative transfer equations for synchrotron radiation using as inputs the RMHD solutions. These simulations show a top-down emission asymmetry produced by …
Spin-orbital polarization of Majorana edge states in oxides nanowires
2020
We investigate a paradigmatic case of topological superconductivity in a one-dimensional nanowire with $d-$orbitals and a strong interplay of spin-orbital degrees of freedom due to the competition of orbital Rashba interaction, atomic spin-orbit coupling, and structural distortions. We demonstrate that the resulting electronic structure exhibits an orbital dependent magnetic anisotropy which affects the topological phase diagram and the character of the Majorana bound states (MBSs). The inspection of the electronic component of the MBSs reveals that the spin-orbital polarization generally occurs along the direction of the applied Zeeeman magnetic field, and transverse to the magnetic and or…
Polarization microscopy as a tool for quantitative evaluation of collagen using picrosirius red in different stages of CKD in cats
2016
Chronic kidney disease (CKD) is a relevant disease in feline clinic. The tubulointerstitial damage, with collagen deposition and fibrosis, is an important result of this process. The aim of this study was to quantify and correlate the deposition of collagen and severity of interstitial fibrosis (IF) in the kidney from cats in different stages of CKD. Kidney fragments from 10 adult cats with CKD were analyzed and stained by Masson's trichrome (MT) and Picrosirius red (PSR) for circular polarized microscopy. Random quantitative analysis was performed on MT sections to classify the degree of IF, per field area, with and without circular polarization. Statistics correlations were performed by S…
Spontaneous Cingulate High-Current Spikes Signal Normal and Pathological Pain States
2019
Prominent 7–12 Hz oscillations in frontal cortical networks in rats have been reported. However, the mechanism of generation and the physiological function of this brain rhythm have not yet been clarified. Multichannel extracellular field potentials of the ACC were recorded and analyzed using the current source density method in halothane-anesthetized rats. Spontaneous high-current spikes (HCSs) were localized in the deep part of layer II/III and upper part of layer V of the ACC. The frequency of HCSs in the ACC was 7–12 Hz, with an amplitude of 6.5 ± 0.76 mV/mm(2) and duration of 55.24 ± 2.43 ms. The power density significantly decreased (84.56 ± 6.93%, p < 0.05, t test) after pinching the…
Neurotransmitters involved in the fast inhibitory junction potentials in mouse distal colon
2003
We investigated, in murine colon circular muscle, the role of adenosine 5′-triphosphate (ATP) and pituitary adenylate cyclase activating peptide (PACAP) as inhibitory neurotransmitters of the fast component of nerve-evoked inhibitory junction potential (fast IJP). Fast IJP was antagonised by apamin or suramin, abolished by desensitisation with the P2Y receptor agonist, adenosine 5′-O-2-thiodiphosphate (ADPβS), unaffected by desensitisation with P2X receptor agonist, α,β-methylene ATP (α,β-meATP), and reduced by PACAP-(6-38), a PACAP receptor antagonist. ATP induced membrane hyperpolarization resistant to tetrodotoxin, Nω-nitro-L-arginine methyl ester (L-NAME) or PACAP-(6-38), but antagonise…