Thermomagnetic irreversibility and magnetic short range ordering in Mn 2.5 Co 0.5 O 4 tetragonal spinel thin films J. Appl. Phys. 107, 09E152 (2010); 10.1063/1.3364051 Room-temperature ferrimagnetic semiconductor 0.6 Fe Ti O 3 • 0.4 Fe 2 O 3 solid solution thin films

Using the electric field to manipulate the magnetization of materials is a potential way of making low-power-consumption nonvolatile magnetic memory devices. Despite concentrated effort in the last 15 years on magnetic multilayers and magnetoelectric multiferroic thin films, there has been no report on the reversal of out-of-plane magnetization by an electric field at room temperature without the aid of an electric current. Here, we report direct observation of out-of-plane magnetization reversal at room temperature by magnetic force microscopy after electric polarization switching of cobalt-substituted bismuth ferrite thin film grown on (110) o -oriented GdScO 3 substrate. A striped pattern of ferroelectric and weakly ferromagnetic domains was preserved after reversal of the out-of-plane electric polarization.

Oxyhydride SrVO2H epitaxial thin films were fabricated on SrTiO3 substrates via topotactic hydridation of oxide SrVO3 films using CaH2. Structural and composition analyses suggested that the SrVO2H film possessed one-dimensionally ordered V-H−-V bonds along the out-of-plane direction. The synthesis temperature could be lowered by reducing the film thickness, and the SrVO2H film was reversible to SrVO3 by oxidation through annealing in air. Photoemission and X-ray absorption spectroscopy measurements revealed the V3+ valence state in the SrVO2H film, indicating that the hydrogen existed as hydride. Furthermore, the electronic density of states was highly suppressed at the Fermi energy, consistent with the prediction that tetragonal distortion induces metal to insulation transition.

Achieving high mobility in Sno 2 , which is a typical wide gap oxide semiconductor, has been pursued extensively for device applications such as field effect transistors, gas sensors, and transparent electrodes. In this study, we investigated the transport properties of lightly Ta-doped SnO 2 (Sn 1−x ta x o 2 , TTO) thin films epitaxially grown on TiO 2 (001) substrates by pulsed laser deposition. The carrier density (n e ) of the TTO films was systematically controlled by x. optimized tto (x = 3 × 10 −3 ) films with n e ~ 1 × 10 20 cm −3 exhibited a very high Hall mobility (μ H ) of 130 cm 2 V −1 s −1 at room temperature, which is the highest among Sno 2 films thus far reported. The μ H value coincided well with the intrinsic limit of μ H calculated on the assumption that only phonon and ionized impurities contribute to the carrier scattering. The suppressed grain-boundary scattering might be explained by the reduced density of the {101} crystallographic shear planes.Tin dioxide (SnO 2 ) has been extensively studied as a practical transparent oxide semiconductor in various applications such as field-effect transistors 1,2 , gas sensors 3-5 , and transparent electrodes 6-8 . Hall mobility (μ H ) is a key parameter in determining the performance of such devices, and the μ H values of bulk SnO 2 single crystals are in the range of 70 to 260 cm 2 V −1 s −1 at room temperature 9-11 . However, SnO 2 thin films show a rather low μ H of less than 100 cm 2 V −1 s −1 even in well-optimized epitaxial films 12,13 , which limits the practical use of SnO 2 .The lower μ H in SnO 2 epitaxial thin films is primarily attributable to the lack of lattice-matched substrates. Thus far, corundum Al 2 O 3 and rutile TiO 2 have been widely used as the substrates for the epitaxial growth 14,15 of SnO 2 . Particularly, Al 2 O 3 , with a high thermal and chemical stability, is suitable for the growth of SnO 2 thin films at high temperatures, but the SnO 2 thin films deposited on Al 2 O 3 suffer from lowered crystallinity owing to the difference between the crystal structures of the film and substrate. For example, very low μ H values are frequently observed for epitaxial SnO 2 films on Al 2 O 3 . TiO 2 shares the same rutile structure as SnO 2 , but it has a relatively large lattice-mismatch with SnO 2 , which is 3.1% and 7.7% for the a-axis and c-axis, respectively. Indeed, it was reported that μ H of the undoped SnO 2 film with (001) orientation on TiO 2 (001) was limited to a rather small value 16 , that is, ~40 cm 2 V −1 s −1 . To overcome the above-mentioned difficulty, very thick self-buffer layers 12,13 have been employed to grow high-μ H epitaxial SnO 2 films on Al 2 O 3 .Another important factor for achieving high μ H is to control the carrier density (n e ) because carriers play two competing roles in μ H ; an increase in n e enhances the screening of the Coulomb scattering potential and thus increases μ H , whereas an increased amount of dopants suppresses μ H owing to impurity scattering. To date, much effort has been made to g...

Zinc oxynitride (ZnOxNy) has attracted much attention as an amorphous semiconductor with high electron mobility. Recent studies reported that ZnOxNy thin films grown by sputtering contained nanocrystals, which might reduce their electron mobility through grain boundary scattering. In this study, we fabricated amorphous ZnOxNy thin films on a glass substrate by a less-energetic nitrogen-plasma-assisted pulsed laser deposition (PLD) to suppress the formation of the nanocrystals. Grown by PLD under optimized conditions, these ZnOxNy thin films exhibited extremely flat surfaces with a root-mean-squared roughness (Rrms) of less than 0.3 nm. The Hall mobility of these films exceeded 200 cm2 V−1 s−1 at a critical carrier concentration of ∼1 × 1019 cm−3, which was twice as high as the reported values for sputter-deposited films. Meanwhile, the mobility of films with larger Rrms was limited to ∼160 cm2 V−1 s−1 even at the critical carrier concentration and comparable with that of the sputter-deposited ZnOxNy films. The substantial enhancement in mobility in extremely flat ZnOxNy films demonstrated that suppressing the formation of nanocrystals is the key to fabricating amorphous ZnOxNy thin films with very high mobility.