Growth of ferromagnetic semiconducting cobalt-doped anatase titanium thin films

Abstract

Heteroepitaxial and polycrystalline anatase Ti1−xCoxO2 (0.0⩽x⩽1.0) thin films were prepared by soft chemical processing on LaAlO3 (001) and thermally oxidized silicon substrates and the crystallinity and magnetic properties were investigated. X-ray diffraction (XRD) spectrum of the Ti1−xCoxO2 films on LaAlO3 (001) substrate shows (004) and (008) peaks of heteroepitaxy anatase without any impurity phase. The full-width at half maximum of the (004) peak rocking curve is 0.4°. The XRD patterns of thin films deposited on the SiO2/Si(001) substrate are anatase type polyscrystalline structure. Microstructural characterization on Ti1−xCoxO2 thin film employing atomic force microscope showed island type grains in 20 nm in size and the surface roughness of typical thin films was 1.5 nm. Sharp hysteresis loops, indicating a well-ordered ferromagnetic structure, appeared in the magnetization versus magnetic field curves when the magnetic field was applied in the plane of the film. This result clearly indicates that the anatase Ti1−xCoxO2 thin films fabricated on LaAlO3 (001) by soft chemical process have crystal quality equivalent to high-vacuum technique.

Structural and magnetic property of Co-doped–ZnO thin films prepared by pulsed laser deposition

“…The saturation magnetization (M s ) of the film deposited at 100 • C and 600 • C are 42 emu/cm 3 and 22 emu/cm 3 , respectively. The values of M s are much lower compared to those reported ones by Shim and Punnoose [6][7][8]. The lower M s values might indicate that diffusion or the substitution has increased when the deposition temperature is set to 600 • C. The inset of Fig.…”

“…Chambers et al [5] stated that n-type is attractive for spintronic because electrons exhibit a long spin relaxation time. Many researchers [6][7][8] in this area have also reported the promising of spintronics with ferromagnetic property at room temperature.…”

Theory of dopants and defects in Co-dopedTiO2anatase

“…2,3,4,5,6,7,8,9 One promising line of inquiry is to understand first the role of dopants and native defects in the TiO 2 host. For example, the location of Co dopants in this material (substitutional versus interstitial), their oxidation state, and their magnetic properties have been the subject of intense scrutiny.…”

Formation of Co nanoclusters in epitaxial Ti0.96Co0.04O2 thin films and their ferromagnetism

“…However, Shinde et al 8 measured the ion-channeling spectra and temperature-dependent magnetization of the Co:TiO 2 films grown by the pulsed laser deposition, but suggested that the FM most likely arises from Co nanocluster formation.…”

“…This work generated great interest in the DMS community, since it could open possibilities to create new multifunctional oxides which utilize the spin polarized carriers. [5][6][7][8][9][10] Chambers et al 6 reported the magnetic and structural properties of the Co:TiO 2 films grown by the oxygen plasma assisted MBE and claimed that the FM should be intrinsic.…”