Ultrathin Fe3O4 epitaxial films on wide bandgap GaN(0001)

Ultrathin films of magnetite (Fe3O4) have been grown epitaxially on wurtzite wide bandgap semiconductor GaN(0001) surfaces using molecular-beam epitaxy. Reflection high-energy electron-diffraction patterns show a (111) orientation of the Fe3O4 films and in-plane epitaxial relationship of < 1 (1) over bar0 >(Fe3O4)parallel to < 11 (2) over bar0 >(GaN) and < 11 (2) over bar >(Fe3O4)parallel to < 1 (1) over bar 00 >(GaN) with the GaN(0001). X-ray photoelectron spectroscopy and x-ray magnetic circular dichroism confirm the growth of stoichiometric Fe3O4, instead of gamma-Fe2O3. The magnetic hysteresis loops and saturation magnetization M-s obtained by superconducting quantum interference device at room temperature show fast saturation of the Fe3O4 films with the magnetization close to that of the bulk single-crystal value. In-plane magnetoresistance (MR) measurements reveal negligibly small MR effects, further indicating that the films are free from antiphase boundaries.