Preparation and characterization of epitaxial Fe(001) thin films on GaAs(001)-based LED for spin injection

Epitaxial growth and interfacial magnetism of spin aligner for remanent spin injection: [Fe/Tb]n/Fe/MgO/GaAs-light emitting diode as a prototype system

“…13 The existence of a strong out-of-plane component of the Fe magnetic moment Fe at and near the Fe͑001͒/MgO͑001͒ interface in the ͓Fe/ Tb͔ n / Fe/ MgO/ GaAs tunneling structure is not at all trivial. We obtain ͗⌰͘ =46Ϯ 5°at RT and ͗⌰͘ =30Ϯ 5°at 4.2 K. This proves that the Fe spins at the Fe͑001͒/MgO͑001͒ interface ͑and the bcc Fe layers in the Fe/Tb multilayer͒ have a considerable out-of-plane component at RT and even more so at 4.2 K. At RT, the present ͗⌰͘ value is considerably smaller than the angle ͗⌰͘ = 53°obtained on similar ͓Fe/ Tb͔ 10 / Fe͑001͒ contacts deposited on a GaAs͑001͒-LED without the MgO͑001͒ tunnelling layer.…”

Spin injection light-emitting diode with vertically magnetized ferromagnetic metal contacts

“…Tb/bcc-Fe multilayers are known to exhibit spontaneous out-of-plane magnetization [17][18][19] induced by perpendicular magnetic anisotropy at the Tb/ Fe interfaces. 20,21 We verified by polar magnetic hysteresis loop measurements and 57 Fe-tracer layer Mössbauer spectroscopy that a significant perpendicular magnetization component is present in the Tb/ Fe multilayer and in the epitaxial Fe͑001͒ film at and below 300 K. 22 The electrical operation of our LED structure was analyzed by measuring a current versus voltage ͑I-V͒ curve. It is shown in Fig.…”

“…We like to emphasize that the Curie temperature of our epitaxial Fe͑001͒ film and the Fe layers in the Tb/ Fe multilayer is much higher than 300 K, since the 57 Fe hyperfine magnetic field at 300 K was found to be nearly the same as that of bulk bcc Fe. 22 Regarding the measured temperature dependence of the circular polarization it is important to notice again that the measured circular polarization is only equivalent to the spin polarization of the recombining electrons in the active medium and therefore can only give a lower limit of the injected spin polarization. Apart from the injection efficiency and spin relaxation during transport the measured spin polarization depends, in particular, on the ratio of carrier lifetime to the spin relaxation time, which usually has a very strong dependence on temperature as well as the QW material.…”

Application of Mössbauer spectroscopy in magnetism

“…Our earlier in situ CEMS measurements in UHV have demonstrated that epitaxial Fe(001) island growth on GaAs(001) occurs below a critical percolation thickness of ∼4 ML Fe, combined with superparamagnetism, while smooth closed Fe(001) films are formed above that critical thickness [106]. The incident γ-ray was perpendicular to the film surface [112] We have employed CEMS and 57 Fe probe layers at the Fe/GaAs and Fe/GaAs(001)-LED interface as a standard diagnostic tool for the characterization of the structural and magnetic state of the interface region [107][108][109][110]. The substrate surfaces were Ga-terminated in the case of GaAs(001)-(4 × 6) substrates and cleaned in UHV by cycles of Ar + sputtering and annealing, following Ref.…”

“…[109,110]. It is well known that bcc-Fe layers in nanoscale Fe/Tb multilayers exibit PMA [26,[116][117][118][119][120][121][122][123][124][125] due to interface anisotropy.…”