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

Abstract

Spin injection light-emitting diode with vertically magnetized ferromagnetic metal contactsWe have successfully grown and characterized ͓Fe/ Tb͔ 10 / Fe͑001͒ / 57 Fe͑001͒ / MgO͑001͒ multilayer contacts on a GaAs-based light emitting diode. Using 57 Fe conversion-electron Mössbauer spectroscopy at room temperature ͑RT͒ and at 4.2 K, we provide atomistic proof of large perpendicular Fe spin components in zero external field at and below RT at the 57 Fe͑001͒ / MgO͑001͒ interface. Further, indirect evidence of large interfacial Fe atomic moments is provided. Our contacts serve as a prototype spin aligner for remanent electrical spin injection at RT.

Application of Mössbauer spectroscopy in magnetism

“…The relative in-plane Fe atomic distance (relative to the Pd(110)-substrate atomic distance) perpendicular to the scattering plane has been determined as a function of the 57 Fe film thickness from the distance of the RHEED streaks in reciprocal space. This demonstrated the stabilization of the metastable face-centered tetragonal (fct) Fe structure on Pd (110) at small Fe film thickness ( ≤∼3 ML Fe) due to the in-plane Fe lattice expansion by the Pd substrate [35]. This lattice expansion was found to be reduced with increasing Fe film thickness.…”

“…The other Mössbauer parameters are significantly different from those of bulk bcc Fe (also at 25 K : B hf = 33.8 ± 0.2T, 2ε = 0mm/s). In both Fe/Pd (110) films, the magnitude of the hyperfine field is clearly enhanced relative to that of bulk bcc Fe. For 3 ML Fe/Pd (110), the value of B peak hf = 39.2T is the largest hyperfine field ever observed for Fe films on metallic substrates.…”

“…Fe on Pd(001) is the most studied system, experimentally [43,44] and theoretically [45,46]. Other substrate orientations, such as Pd (110), have attracted less attention [47].…”

“…The 57 Co(Rh) source of ∼40 mCi (or ∼1.5 GBq) activity was outside of the UHV system, and the 14.4-keV γ-radiation was transmitted through a UHV-tight Be window in normal incidence to the film plane. LEED and RHEED provided evidence for initial epitaxial (pseudomorphic) 57 Fe film growth on Pd (110). The relative in-plane Fe atomic distance (relative to the Pd(110)-substrate atomic distance) perpendicular to the scattering plane has been determined as a function of the 57 Fe film thickness from the distance of the RHEED streaks in reciprocal space.…”

“…[35]. After 57 Fe film preparation and LEED/RHEED studies the sample was transferred (110) measured in situ in UHV at T = 25 K. The corresponding distribution of hyperfine magnetic fields, P(B hf ), is shown on the right-hand side. The incident γ-ray was perpendicular to the film surface.…”