Nanoscaled systems studied by Mössbauer spectroscopy: Fe/Tb multilayer contacts on InAs(001)

The successful fabrication and characterization of ferromagnetic Fe/Tb multilayer contacts with perpendicular magnetic anisotropy on clean and well-ordered InAs(001) surfaces is reported. First, an epitaxial 57Fe(001) thin film was grown directly on InAs(001)- (4×2) at TS≈40∘C, as evidenced by reflection high-energy electron diffraction (RHEED), followed by a polycrystalline Fe/Tb multilayer. The Fe spin structure was investigated by conversion electron Mössbauer spectroscopy at room temperature, 77 and 10 K in combination with the 57Fe tracer layer technique. At low temperature, the Fe spins in the epitaxial interfacial 57Fe(001) layer were found to form an average tilting angle less than 30∘ with respect to the surface normal direction (cone state), indicating strong perpendicular Fe spin components. This observation is supported by superconducting quantum interference device (SQUID) magnetometry. Such contacts are a potential candidate for the optical detection of electron spin injection from a remanent magnetic state into the semiconductor.