Growth and magnetic properties of ultrathin single crystal Fe₃O₄ film on InAs(100)

Abstract

Different thickness of ultrathin films of magnetite (Fe3O4) have been grown epitaxially on zinc‐blende narrow band‐gap semiconductor InAs(100) surfaces by in situ post‐growth annealing of ultrathin epitaxial Fe films at 300 °C in an oxygen partial pressure of 5 × 10−5 mbar. Reflection high‐energy electron‐diffraction patterns show that the epitaxial Fe3O4 films have been rotated by 45° in‐plane to match the InAs substrates. The magnetic hysteresis loops obtained by magneto‐optic Kerr effect (MOKE) shows a in‐plane uniaxial magnetic anisotropy for the ultrathin films, and the global easy axis is rotated from the uniaxial easy [011] direction to the cubic easy [010] direction when the thickness of the film increases.

Interface exchange coupling induced fourfold symmetry planar Hall effect in Fe3O4/NiO bilayers

“…Here we take H c;u ¼ 2K c;u =M and get H c;u ¼ H vol c;u þ 2H surf c;u =d. Separating the volume contribution H vol c;u and the interface contribution H surf c;u may provide a deeper insight into the origin of the uniaxial and cubic magnetic anisotropy of the bilayers [23]. The factor 2 results from the presence of the interfaces Fe 3 O 4 -NiO and the surface of the Fe 3 O 4 layer.…”

Hybrid spintronic materials: Growth, structure and properties

“…GaAs 001 The second approach is post-growth oxidation, in which an Fe film is first deposited on a given substrate, and then oxidized by some oxidizing agent to form Fe oxide. In our present discussion on hybrid spintronic structures, the Fe has been epitaxially grown on GaAs(001) and other SC substrates with or without a MgO interlayer, prior to oxidation [237][238][239][240][241][242][243][244]. This approach leads to ultrathin Fe oxide films of high-quality owing to the oxidation mechanism applied here.…”

“…Progress has been made on integrating half-metallic Fe3O4 with various mainstream SCs including GaAs(001) [237,258], InAs(001) [243,244], GaN(0001) [239,259,260] and MgO-buffered Si(001) [242], which are made possible by the post-annealing oxidation as introduced in the preceding paragraphs. As developed by Lu et al [237], the recipe involved in those fabrications can be generalized as the following two steps: (i) Epitaxial growth of Fe ultrathin film on the SC substrate of interest, followed by (ii) exposure to molecular oxygen with a partial pressure of 5 × 10 -5 to 8 × 10 -4 mbar at a substrate temperature of 500 K. Figure 29 shows as an example the RHEED patterns for Fe3O4/GaAs(001 Another striking property of the Fe3O4-based hybrid spintronic structures lies on the presence of a substrate-dependent UMA, unexpected from the cubic symmetry of the ferrite, as that found in Fe/GaAs.…”

“…On the other hand, it is impossible to establish a direct correlation between the lattice mismatch and the UMA. If one nevertheless singles out Fe3O4/GaAs(001) [237] and Fe3O4/InAs(001) [244], the magnetic easy axes of the UMA in these cases have been observed to differ by 90¡, exactly identical to that for Fe/GaAs(001) [28] versus Fe/InAs(001) [54]. Such an observation is highly crucial because it tentatively suggests that the UMA in these Fe3O4-based hybrid structures might be directly stemmed from their parent Fe-based systems.…”