Off-stoichiometric full-Heusler alloy Co_2 MnAl thin films with different thicknesses are epitaxially grown on GaAs(001) substrates by molecular-beam epitaxy. The composition of the films, close to Co_(1.65)Mn_(1.35)A...Off-stoichiometric full-Heusler alloy Co_2 MnAl thin films with different thicknesses are epitaxially grown on GaAs(001) substrates by molecular-beam epitaxy. The composition of the films, close to Co_(1.65)Mn_(1.35)Al(CMA),is determined by x-ray photoelectron spectroscopy and energy dispersive spectroscopy. Tunable perpendicular magnetic anisotropy(PMA) from 3.41 Merg/cm^3 to 1.88 Merg/cm^3 with the thickness increasing from 10 nm to 30 nm is found,attributed to the relaxation of residual compressive strain. Moreover, comparing with the ultrathin CoFeB/MgO used in the conventional perpendicular magnetic tunnel junction, the CMA electrode has a higher magnetic thermal stability with more volume involved. The PMA in CMA films is sustainable up to 300℃,compatible with semiconductor techniques. This work provides a possibility for the development of perpendicular magnetized full-Heusler compounds with high thermal stability and spin polarization.展开更多
Electric luminescence and its circular polarization in a Co2 MnAl injector-based light emitting diode （LED） has been detected at the transition of e–A0 C , where injected spin-polarized electrons recombine with bou...Electric luminescence and its circular polarization in a Co2 MnAl injector-based light emitting diode （LED） has been detected at the transition of e–A0 C , where injected spin-polarized electrons recombine with bound holes at carbon acceptors. A spin polarization degree of 24.6% is obtained at 77 K after spin-polarized electrons traverse a distance of 300 nm before they recombine with holes bound at neutral carbon acceptors in a p ＋ -GaAs layer. The large volume of the p ＋ -GaAs layer can facilitate the detection of weak electric luminescence （EL） from e–A 0C emission without being quenched at higher bias as in quantum wells. Moreover, unlike the interband electric luminescence in the p＋ -GaAs layer, where the spin polarization of injected electrons is destroyed by a very effective electron–hole exchange scattering （BAP mechanism）, the spin polarization of injected electrons seems to survive during their recombination with holes bound at carbon acceptors.展开更多
基金Supported by the National Key Research and Development Program of China under Grant Nos 2017YFB0405701 and2018YFB0407601the National Natural Science Foundation of China under Grant Nos U1632264 and 11874349the Key Research Project of Frontier Science of the Chinese Academy of Sciences under Grant Nos QYZDY-SSW-JSC015 and XDPB12
文摘Off-stoichiometric full-Heusler alloy Co_2 MnAl thin films with different thicknesses are epitaxially grown on GaAs(001) substrates by molecular-beam epitaxy. The composition of the films, close to Co_(1.65)Mn_(1.35)Al(CMA),is determined by x-ray photoelectron spectroscopy and energy dispersive spectroscopy. Tunable perpendicular magnetic anisotropy(PMA) from 3.41 Merg/cm^3 to 1.88 Merg/cm^3 with the thickness increasing from 10 nm to 30 nm is found,attributed to the relaxation of residual compressive strain. Moreover, comparing with the ultrathin CoFeB/MgO used in the conventional perpendicular magnetic tunnel junction, the CMA electrode has a higher magnetic thermal stability with more volume involved. The PMA in CMA films is sustainable up to 300℃,compatible with semiconductor techniques. This work provides a possibility for the development of perpendicular magnetized full-Heusler compounds with high thermal stability and spin polarization.
基金Project supported by the National Basic Research Program of China (Grant No. 2011CB932901)the National Natural Science Foundation of China (GrantNo. 60836002)
文摘Electric luminescence and its circular polarization in a Co2 MnAl injector-based light emitting diode （LED） has been detected at the transition of e–A0 C , where injected spin-polarized electrons recombine with bound holes at carbon acceptors. A spin polarization degree of 24.6% is obtained at 77 K after spin-polarized electrons traverse a distance of 300 nm before they recombine with holes bound at neutral carbon acceptors in a p ＋ -GaAs layer. The large volume of the p ＋ -GaAs layer can facilitate the detection of weak electric luminescence （EL） from e–A 0C emission without being quenched at higher bias as in quantum wells. Moreover, unlike the interband electric luminescence in the p＋ -GaAs layer, where the spin polarization of injected electrons is destroyed by a very effective electron–hole exchange scattering （BAP mechanism）, the spin polarization of injected electrons seems to survive during their recombination with holes bound at carbon acceptors.
