676 research outputs found
Magnetic tunnel junctions with yttrium oxide barrier
No full textMagnetic tunnel junctions have been studied, with YOx barriers prepared by plasma oxidation of a 1.5 nm Y film. We report their junction area resistance, tunnel magnetoresistance (TMR) and barrier parameters (height and thickness) as a function of the oxidation time. For the optimum oxidation time, TMR values of similar to25% are obtained at room temperature and similar to44% at low temperature (5 K). The barrier height extracted from the current-voltage curves, is close to 1 eV, which is less than half of what is usually reported for AlOx-based junctions. Structural and topographical characterization of the multilayes revealed that the YOx layer is amorphous with well-defined, smooth, and correlated interfaces with the ferromagnetic electrodes. (C) 2003 American Institute of Physics
Analysis of the magnetotransport channels in tunnel junctions with amorphous
No full textThis work concerns the temperature and bias dependence of the
magnetotransport properties of \chem{Al} oxide-based tunnel
junctions with an amorphous \chem{Co_{60}Fe_{20}B_{20}} soft
ferromagnetic electrode and \chem{CoFe_{10}}-based
polycrystalline hard electrode. The junctions present high tunnel
magnetoresistance of % at room temperature and
% at 5\un{K}. A model that takes magnon-assisted
inelastic tunneling into account fits satisfactorily the parallel
(P) and antiparallel (AP) conductance as a function of
temperature. The extracted fitting parameters are then used to
reproduce the low-bias anomaly of the P and AP conductance at low
temperature
Large tunnel magnetoresistance with plasma oxidized MgO barrier
No full textThis work focuses on magnetic tunnel junctions with a polycrystalline MgO barrier, prepared by plasma oxidation. Combined with Co50Fe50 ferromagnetic electrodes, a large tunnel magnetoresistance (TMR) of 60% is obtained at room temperature. The TMR effect is comparable to state-of-the-art Al oxide barriers with amorphous CoFeB electrodes. It is also found to decrease with the MgO thickness. Two most significant advantages of the MgO junctions are pointed out: (a) The resistance-area product is approximately two orders of magnitude lower than for AlOX- based junctions of the same thickness. (b) MgO presents unsurpassed thermal stability for high annealing temperatures (up to 370 degrees C) and long annealing periods. In addition, for small, patterned elements, we have tested the switching behavior of the soft electrode grown on the polycrystalline MgO barrier. (c) 2005 American Institute of Physics
Tunnel junctions with yttrium oxide barrier and various ferromagnetic electrodes
No full textThis work concerns tunnel junctions with yttrium oxide barrier prepared by plasma oxidation of a 1.5-nm Y film. The magnetoresistive properties of the junctions were studied as a function of the ferromagnetic (FM) electrodes in contact with the barrier, such as CoFe, Py (permalloy), and CoFeNiSiB. The maximum measured tunnel magnetoresistance (TMR) effect was 25% at room temperature-raised to over 40 % at 5 K. The TMR and the tunnel barrier characteristics (thickness, height, and asymmetry) depend significantly on the FM electrodes and the annealing temperature. Barrier heights of less than 1 eV have been extracted in all cases -two to three times lower than the ones reported for AlOx-based junctions
Modal Properties of Photonic Crystal Cavities and Applications to Lasers
No full textPhotonic crystal cavities enable strong light–matter interactions, with numerous applications, such as ultra-small and energy-efficient semiconductor lasers, enhanced nonlinearities and single-photon sources. This paper reviews the properties of the modes of photonic crystal cavities, with a special focus on line-defect cavities. In particular, it is shown how the fundamental resonantmode in line-defect cavities gradually turns from Fabry–Perot-like to distributed-feedback-like with increasing cavity size. This peculiar behavior is directly traced back to the properties of the guided Bloch modes. Photonic crystal cavities based on Fano interference are also covered. This type of cavity is realized through coupling of a line-defect waveguide with an adjacent nanocavity, with applications to Fano lasers and optical switches. Finally, emerging cavities for extreme dielectric confinement are covered. These cavities promise extremely strong light–matter interactions by realizing deep sub-wavelength mode size while keeping a high quality factor
Extramedullary plasmacytoma in a horse with ptyalism and dysphagia
No full textA Clydesdale mare was examined for weight loss, inappetence, ptyalism, and dysphagia. The main abnormality revealed by serum biochemistry was a marked hyperglobulinemia, and protein electrophoresis revealed a monoclonal gammopathy in the gamma region. The urine was positive for Bence Jones proteins. These findings suggested a plasma cell tumor. The neoplasm could not be located with extensive antemortem examination. At postmortem, neoplastic cells morphologically compatible with plasma cells and positive for equine IgG with imunoperoxidase staining infiltrated the pericardium, mediastinal stromal tissues, adrenal glands, meninges, atrioventricular valves, aorta, abdominal and thoracic fat, and nerves, including the trigeminal nerve. The neoplastic cells invading the cranial nerves were responsible for many of the presenting signs.PT: J; CR: BARLOGIE B, 1995, WILLIAMS HEMATOLOGY, P1109 BAUER JD, 1974, CLIN LAB METHODS, P15 BRAUND KG, 1978, J AM VET MED ASSOC, V172, P1407 BRAUND KG, 1979, J AM VET MED ASSOC, V174, P1321 CALNEK BW, 1991, DIS POULTRY, P342 DIMOPOULOS MA, 1994, BLOOD, V83, P1452 DREW RA, 1974, EQUINE VET J, V3, P131 DUNCAN JR, 1994, VET LAB MED CLIN PAT, P112 DUNCAN JR, 1994, VET LAB MED CLIN PAT, P63 EDWARDS DF, 1993, J VET INTERN MED, V7, P169 HENRY M, 1994, J AM VET MED ASSOC, V194, P392 JACKSON MW, 1994, J AM VET MED ASSOC, V204, P404 KENT JE, 1990, EQUINE VET J, V22, P373 MANDEL NS, 1994, J AM ANIM HOSP ASSOC, V30, P603 TRAUBDARGATZ J, 1985, EQUINE VET J, V17, P373; NR: 15; TC: 9; J9: J VET DIAGN INVEST; PG: 3; GA: 312MPSource type: Electronic(1
Operando Optical Microscopy of Dead Lithium Growth in Anode-Less Configuration
No full textThere is an increasing demand to improve battery safety and performance as part of the global push to convert the small electronics and transportation sector to infrastructures based on electricity. This work follows the deposition of lithium metal in anode-less conditions by an operando optical microscope using a transparent indium tin oxide-polyethylene terephthalate (ITO-PET) window as the current collector in a readily-available electrochemical set-up. The mechanism of Li metal nucleation strongly depends on the selected current densities (C/40 and 2C). After the deposition of the solid electrolyte interface (SEI), Li nucleates from mossy to needle morphology. Moreover, layer-by-layer growth of dead Li in voids is monitored by following its accumulation upon cycling. Dead Li deposits in residual hollow structures, especially when high current densities are applied. These optical observations are coupled with computer vision analyses to evaluate the average size of the Li deposits: smaller Li nuclei plate when high C-rate is applied. The results here described provide insights into a new electrochemical cell concept that enables to elucidate the influence of spatial inhomogeneities of the lithophilic ITO-PET surface on the mechanism of Li nucleation and plating
Non-Perturbative Renormalisation and Running of BSM Four-Quark Operators in QCD
No full textWe perform a non-perturbative study of the scale-dependent renormalisation factors of a complete set of dimension-six four-fermion operators without power subtractions. The renormalisation-group (RG) running is determined in the continuum limit for a specific Schrödinger Functional (SF) renormalisation scheme in the framework of lattice QCD with two dynamical flavours ( ). The theory is regularised on a lattice with a plaquette Wilson action and -improved Wilson fermions. For one of these operators, the computation had been performed in Dimopoulos et al. (JHEP 0805, 065 (2008). arXiv:0712.2429 ), the present work completes the study for the rest of the operator basis, on the same simulations (configuration ensembles). The related weak matrix elements arise in several operator product expansions, in transitions they contain the QCD long-distance effects, including contributions from beyond-Standard Model (BSM) processes. Some of these operators mix under renormalisation and their RG-running is governed by anomalous dimension matrices. In Papinutto et al. (Eur Phys J C 77(6), 376 (2017). arXiv:1612.06461 ) the RG formalism for the operator basis has been worked out in full generality and the anomalous dimension matrix has been calculated in NLO perturbation theory. Here the discussion is extended to the matrix step-scaling functions, which are used in finite-size recursive techniques. We rely on these matrix-SSFs to obtain non-perturbative estimates of the operator anomalous dimensions for scales ranging from to .We perform a non-perturbative study of the scale-dependent renormalisation factors of a complete set of dimension-six four-fermion operators. The renormalisation-group (RG) running is determined in the continuum limit for a specific Schr\"dinger Functional (SF) renormalisation scheme in the framework of lattice QCD with two dynamical flavours ( ). The theory is regularised on a lattice with a plaquette Wilson action and -improved Wilson fermions. For one of these operators, the computation had been performed in ref. [1]; the present work completes the study for the rest of the operator basis, on the same simulations (configuration ensembles). The related weak matrix elements arise in several operator product expansions; in transitions they contain the QCD long-distance effects, including contributions from beyond-Standard Model (BSM) processes. Some of these operators mix under renormalisation and their RG-running is governed by anomalous dimension matrices. In ref. [2] the RG formalism for the operator basis has been worked out in full generality and the anomalous dimension matrix has been calculated in NLO perturbation theory. Here the discussion is extended to the matrix step-scaling functions (matrix-SSFs), which are used in finite-size recursive techniques. We rely on these matrix-SSFs to obtain non-perturbative estimates of the operator anomalous dimensions for scales ranging from to
Co-rich magnetic amorphous films and their application in magnetoelectronics
No full textThree kinds of Co-rich magnetic amorphous films of CoFeB, CoFeNiSiB, and CoFeHfO were prepared by magnetron sputtering and applied as soft ferromagnetic (FM) electrodes in tunneling magnetoresistance (TMR) devices. Initial results exhibit a large room-temperature TMR effect of approximately 50%. The high effect can be attributed to interfacial coherence between the amorphous barrier-electrode layers and, accordingly, suggests a high local spin polarization possibly associated with strong nearest-neighbor spin correlations of the magnetic atoms. The magnetotransport behavior may be governed by details of the local spin environment in magnetic amorphous electrodes due to their short electron mean-free path (similar to 3-5 angstrom). The annealing effect on TMR was found to be more pronounced due to the atomic cooperative structural relaxation and more thermally stable compared with the polycrystalline electrode junctions. Additionally, the use of the magnetic oxide electrode CoFeHfO has shown that the relevant FM electrode-barrier interface becomes insensitive to the oxygen, which simplifies the oxidation process used for the oxide barrier fabrication
“Salvage treatment” for infections by extensively- and pan-drug-resistant pathogens is common and often sub-optimal
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