Highly Spin-Polarized Room-Temperature Tunnel Injector for Semiconductor Spintronics using MgO(100)

Solid State and Photonics Laboratory, Stanford University, Palo Alto, California, United States
Physical Review Letters (Impact Factor: 7.51). 03/2005; 94(5):056601. DOI: 10.1103/PhysRevLett.94.056601
Source: PubMed


The spin polarization of current injected into GaAs from a CoFe/MgO(100) tunnel injector is inferred from the electroluminescence polarization from GaAs/AlGaAs quantum well detectors. The polarization reaches 57% at 100 K and 47% at 290 K in a 5 T perpendicular magnetic field. Taking into account the field dependence of the luminescence polarization, the spin injection efficiency is at least 52% at 100 K, and 32% at 290 K. We find a nonmonotonic temperature dependence of the polarization which can be attributed to spin relaxation in the quantum well detectors.

Download full-text


Available from: James S Harris, Dec 31, 2013
27 Reads
  • Source
    • "The first one is to use a quarter-wave plate. The second possibility is based on the electrical injection of spin-polarized carriers into the active region [1] [2] [3] [4] [5] [6]. The third possibility is to modify the local electromagnetic field, for example, using chiral liquid crystals [7] [8] [9]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigate theoretically the polarization properties of the quantum dot's optical emission from chiral photonic crystal structures made of achiral materials in the absence of external magnetic field at room temperature. The mirror symmetry of the local electromagnetic field is broken in this system due to the decreased symmetry of the chiral modulated layer. As a result, the radiation of randomly polarized quantum dots normal to the structure becomes partially circularly polarized. The sign and degree of circular polarization are determined by the geometry of the chiral modulated structure and depend on the radiation frequency. A degree of circular polarization up to 99% can be achieved for randomly distributed quantum dots, and can be close to 100% for some single quantum dots.
    Optics Letters 12/2014; 40(7). DOI:10.1364/OL.40.001528 · 3.29 Impact Factor
  • Source
    • "For samples capped with Au and at 7.1 to 28 ML, the uniaxial anisotropy is clearly visible and coexists with a four-fold cubic magnetocrystalline anisotropy. Its global easy axis is along [0] [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] while [010] and [001] directions are equally magnetic hard. Such orientation of the easy and hard axes can also be found in the MgO capped samples within the same range. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic anisotropies of Fe/MgO/GaAs(100) hybrid structure with two different nonmagnetic capping materials, Au and MgO have been studied by ferromagnetic resonance (FMR). A uniaxial anisotropy, unexpected from the crystal structure was observed in the ultrathin films for both capping materials. Its global easy axis is along [0-11] direction while two (010) directions are equally magnetic hard regardless of the overlayer material. The in-plane uniaxial anisotropy (in-plane cubic anisotropy) of the Au capped samples is stronger (weaker) than that of the MgO capped ones within the range of t <sub>Fe</sub> = 7.1 to 28 ML. This suggests that the MgO overlayer suppresses the uniaxial anisotropy faster than the Au overlayer.
    IEEE Transactions on Magnetics 12/2008; 44(11-44):2907 - 2910. DOI:10.1109/TMAG.2008.2002195 · 1.39 Impact Factor
  • Source
    • "There are two big challenges in the realization of a spin-FET [2]: (i) efficient spin-polarized current injection, and (ii) spin-dependent conductance modulation by the applied electric field. In spite of the constant progress in the spin-polarized carrier injection technique [8] [9], the efficiency it is still far from 100%. In turn, the modulation of the spin polarized current is pretty low (about several percent) [10]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We propose and analyze a new kind of nano scale computational architectures using spin waves as a physical mechanism for device interconnection. Information is encoded into the phase of spin waves propagating in a ferromagnetic film — a Spin Wave Bus. We describe several possible logic devices utilizing spin waves. The performance of the proposed devices is illustrated by numerical modeling based on the experimental data for spin wave excitation and propagation in NiFe film. The key advantage of the proposed architectures is that information transmission is accomplished without charge transfer. Potentially, the architectures with Spin Wave Bus may be beneficial in terms of power consumption and resolve the interconnect problem. Another expected benefit is in the enhanced logic functionality. Using phase logic, it is possible to realize a number of logic functions in one device. These advantages make the architectures with a Spin Wave Bus very promising for application in ultra-high-density integrated circuits (more than 1010 devices per square inch).
    Superlattices and Microstructures 09/2005; 38(3-38):184-200. DOI:10.1016/j.spmi.2005.07.001 · 2.10 Impact Factor
Show more