1,188 research outputs found
Decompositions of some twisted Foulkes characters
We decompose the twisted Foulkes characters , or equivalently the plethysm , in the cases where has either two rows or two columns, or is a hook partition
Strongly reduced bias dependence in spin-tunnel junctions obtained by ultraviolet light assisted oxidation
For future implementation of ferromagnetic tunnel junctions, we need a better understanding of the influence of the insulating barrier preparation method on the junction resistance, tunnel magnetoresistance (TMR), and its voltage bias dependence. In this letter, we focus on the bias dependence of junctions (Co-Al2O3-Ni80Fe20) prepared by ultraviolet light assisted in situ oxidation in an O-2 ambient. For an initial Al thickness of 1.3 nm, the resistance times area product of the junctions is 60 k Omega mu m(2), while showing up to 20% TMR at 5 mV bias. The decrease of TMR with bias voltage up to 1 V is remarkably small leading to V-1/2, for which half of the low-bias TMR remains, well over 0.6 V. (C) 2000 American Institute of Physics. [S0003-6951(00)02908-9]
Highly efficient room temperature spin injection in a metal-insulator-semiconductor light emitting diode
We demonstrate highly efficient spin injection at low and room temperature in
an AlGaAs/GaAs semiconductor heterostructure from a CoFe/AlOx tunnel spin
injector. We use a double-step oxide deposition for the fabrication of a
pinhole-free AlOx tunnel barrier. The measurements of the circular polarization
of the electroluminescence in the Oblique Hanle Effect geometry reveal injected
spin polarizations of at least 24% at 80K and 12% at room temperature
Electrical Spin Injection in a Ferromagnetic / Tunnel Barrier/ Semiconductor Heterostructure
We demonstrate experimentally the electrical ballistic electron spin
injection from a ferromagnetic metal / tunnel barrier contact into a
semiconductor III-V heterostructure. We introduce the Oblique Hanle Effect
technique for reliable optical measurement of the degree of injected spin
polarization. In a CoFe / Al2O3 / GaAs / (Al,Ga)As heterostructure we observed
injected spin polarization in excess of 8 % at 80K.Comment: 5 pages, 4 figure
Voltage controlled spin injection in a (Ga,Mn)As/(Al,Ga)As Zener diode
The spin polarization of the electron current in a
p-(Ga,Mn)As-n-(Al,Ga)As-Zener tunnel diode, which is embedded in a
light-emitting diode, has been studied theoretically. A series of
self-consistent simulations determines the charge distribution, the band
bending, and the current-voltage characteristics for the entire structure. An
empirical tight-binding model, together with the Landauer- Buttiker theory of
coherent transport has been developed to study the current spin polarization.
This dual approach allows to explain the experimentally observed high magnitude
and strong bias dependence of the current spin polarization.Comment: Submitted to Phys. Rev. B Rapid Communication
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