216,604 research outputs found

    Quantum steering of electron wave function in an InAs Y-branch switch

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    We report experiments on gated Y-branch switches made from InAs ballistic electron wave guides. We demonstrate that gating modifies the electron wave functions as well as their interference pattern, causing the anti-correlated, oscillatory transconductances. Such previously unexpected phenomenon provides evidence of steering the electron wave function in a multi-channel transistor structure.Comment: 15 pages, including 3 figure

    Perturbative calculation of the scaled factorial moments in second-order quark-hadron phase transition within the Ginzburg-Landau description

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    The scaled factorial moments FqF_q are studied for a second-order quark-hadron phase transition within the Ginzburg-Landau description. The role played by the ground state of the system under low temperature is emphasized. After a local shift of the order parameter the fluctuations are around the ground state, and a perturbative calculation for FqF_q can be carried out. Power scaling between FqF_q's is shown, and a universal scaling exponent ν1.75\nu\simeq 1.75 is given for the case with weak correlations and weak self-interactions.Comment: 12 pages in RevTeX, 12 eps figure

    Soliton self-modulation of the turbulence amplitude and plasma rotation

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    The space-uniform amplitude envelope of the Ion Temperature Gradient driven turbulence is unstable to small perturbations and evolves to nonuniform, soliton-like modulated profiles. The induced poloidal asymmetry of the transport fluxes can generate spontaneous poloidal spin-up of the tokamak plasma.Comment: Latex file, 66 pages, 24 postscript figures included. New section on rotation five new figures, comparison with magnetic pumping dampin

    Anatomy of perpendicular magnetic anisotropy in Fe/MgO magnetic tunnel junctions: First principles insight

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    Using first-principles calculations, we elucidate microscopic mechanisms of perpendicular magnetic anisotropy (PMA)in Fe/MgO magnetic tunnel junctions through evaluation of orbital and layer resolved contributions into the total anisotropy value. It is demonstrated that the origin of the large PMA values is far beyond simply considering the hybridization between Fe-3dandO2porbitalsattheinterfacebetweenthemetalandtheinsulator.Onsiteprojectedanalysisshowthattheanisotropyenergyisnotlocalizedattheinterfacebutitratherpropagatesintothebulkshowinganattenuatingoscillatorybehaviorwhichdependsonorbitalcharacterofcontributingstatesandinterfacialconditions.Furthermore,itisfoundinmostsituationsthatstateswith and O-2p orbitals at the interface between the metal and the insulator. On-site projected analysis show that the anisotropy energy is not localized at the interface but it rather propagates into the bulk showing an attenuating oscillatory behavior which depends on orbital character of contributing states and interfacial conditions. Furthermore, it is found in most situations that states with d_{yz(xz)}and and d_{z^2}charactertendalwaystomaintainthePMAwhilethosewith character tend always to maintain the PMA while those with d_{xy}and and d_{x^2-y^2}charactertendtofavortheinplaneanisotropy.ItisalsofoundthatwhileMgOthicknesshasnoinfluenceonPMA,thecalculatedperpendicularmagneticanisotropyoscillatesasafunctionofFethicknesswithaperiodof2MLandreachesamaximumvalueof3.6mJ/m character tend to favor the in-plane anisotropy. It is also found that while MgO thickness has no influence on PMA, the calculated perpendicular magnetic anisotropy oscillates as a function of Fe thickness with a period of 2ML and reaches a maximum value of 3.6 mJ/m^2$.Comment: 5 pages, 5 figure
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