Xiaoqi Li

University of Science and Technology, Beijing, Peping, Beijing, China

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Publications (4)3.12 Total impact

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    ABSTRACT: Magnetic properties have been studied for Ta/Pt/Co2FeAl0.5Si0.5 (CFAS)/MgO/Pt multilayers to investigate the effects of annealing and MgO thickness on perpendicular magnetic anisotropy (PMA). We show that PMA is very sensitive to the annealing conditions and MgO thickness. Strong PMA with high remanence ratio can be achieved after annealing at 300 °C for just 10 min. The thickness of CFAS (tCFAS) with PMA is strongly dependent on the MgO thickness (tMgO). A large tCFAS with PMA is observed to be 4.8 nm for tMgO = 1.6 nm. The saturation magnetization (Ms) decreases on increasing tMgO with an obviously periodic oscillation, and the periods of oscillation are between 0.2 and 0.3 nm. Moreover, the annealed structure shows good thermal stability and a weaker temperature dependence of the squareness ratio (Mr/Ms) for the samples with thicker MgO.
    Physica Status Solidi (A) Applications and Materials 03/2014; 211(3). · 1.46 Impact Factor
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    ABSTRACT: The current-driven domain wall motion was investigated on permalloy nanowires with different dimensions by micromagnetic simulations. The critical current density increased with the reduction in both the width and thickness of nanowires because of the enhanced hard-axis anisotropy. At a thickness of 5 nm, the critical current density decreased with the reduction of the nanowire width because of the reduced domain wall width.
    Science China: Physics, Mechanics and Astronomy 10/2012; 55(11). · 1.17 Impact Factor
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    ABSTRACT: We report on perpendicular magnetic anisotropy (PMA) in a Pt/Co2FeAl/MgO sandwiched structure with a thick Co2FeAl layer of 2-2.5 nm. The PMA is thermally stable that the anisotropy energy density Ku is 1.3{\times}106 erg/cm3 for the structure with 2 nm Co2FeAl after annealing at 350 oC. The thicknesses of Co2FeAl and MgO layers greatly affect the PMA. Our results provide an effective way to realize relative thick perpendicularly magnetized Heusler alloy films.
    Applied Physics Express - APPL PHYS EXPRESS. 02/2011;
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    ABSTRACT: We have calculated the electronic structures of Co2FeAl1−x Six (101) surface using first-principles method based on the density functional theory. Because of the surface effect, the minority spin band gap at the Fermi level disappears at the surface of bulk Co2FeAl1−x Six . However, beneath the surface, the minority spin gap opens at the Fermi level, which indicates that the electronic structures of Co2FeAl1−x Six (101) become close to that of bulk phase. Accordingly, the Co2FeAl1−x Six (101) surface is a composite tri-layer structure that corresponds to the weakening of half-metallic property in Co2FeAl1−x Six films. Even though, the spin polarization of Co2FeAl1−x Six (101) surface is still larger than that of Co2FeAl or Co2FeSi materials, making Co2FeAl1−x Six a promising spintronics material.
    Rare Metals 31(2). · 0.49 Impact Factor