First, we deposited a metallic multilayer stack consisting of 50 nm of titanium adhesive layer followed by 100 nm of gold layer for electrical contact and a 300 nm layer of titanium or iron on 17 mm × 17 mm Si(001) substrate. We prepared metal/anodized metal oxide/metal junctions with different compositions, as listed in Table 1. Hematite and magnetite have both demonstrated their applicability in oxide-based junctions with the Schottky barrier. Maghemite ( γ-Fe 2O 3) is ferrimagnet with magnetite-like inverse spinel structure and hematite-like stoichiometry, for which the charge neutrality is achieved through the presence of Fe ions vacancies. On the other hand, the hematite ( α-Fe 2O 3) is a semiconductor with a bandgap of 2.0 eV, which is antiferromagnetic below Néel temperature of 950 K and at 260 K undergoes the Morin transition between easy-axis and easy-plane antiferromagnet with small canting between sublattices resulting from Dzyaloshinskii–Moriya interaction. For example, the magnetite has an inverse spinel structure and is a ferrimagnetic half-metal that transforms into insulator below the Verwey transition (∼125 K). Iron oxides show a wide range of magnetic and transport properties. Defects can also induce weak ferromagnetism in paramagnetic titanium oxides, as observed for anatase, rutile, and TiO rock salts. The impact of defects, especially in non-stoichiometric TiO 2, can lead to the n- (oxygen deficient) or p-type (titanium deficient) semiconductors. The nanotubular anodized titanium oxide was shown to form a Schottky barrier between Ti and TiO 2 and the importance of structural defects on semiconducting properties was further investigated recently. The patterned semiconducting oxide layers are increasingly considered as a potential material for photoelectrochemical and photocatalytic purposes, as demonstrated in the case of titanium oxide with a bandgap of ∼3.0–3.2 eV.

Magnetic field effect aluminum oxide