A transparent room-temperature ferromagnetic semiconductor on glass: anatase Co-doped TiO2 oriented thin films with improved electrical conduction

Abstract

We adopted TiO₂ seed layers for thin-film growth of anatase Ti_0.95Co_0.05O_2−δ, a room-temperature ferromagnetic semiconductor, on rigid and flexible (ultrathin) glass substrates. The Ti_0.95Co_0.05O_2−δ thin films with preferred (101) orientation and large crystallographic domains around 50 μm in lateral size showed clear ferromagnetic hysteresis loops in the magnetization curves at 300 K. In addition, their high electrical conductivity and transparency allowed electrical and optical detection of the ferromagnetic signal via the anomalous Hall effect and magneto-optical effect, respectively. Intriguingly, flatter thin films with larger domains were obtained on flexible glass substrates, which were beneficial to achieve higher conductivity and larger anomalous Hall signals, comparable to those in epitaxial thin films.