Hitoshi Tabata 교수

We have formed strained dielectric superlattices of BaTiO3 (BTO) and SrTiO3 (STO) by a pulsed laser deposition technique. A large strain of 400–500 MPa is introduced at the interface between the BTO and STO layers. A large dielectric constant of 900 was observed with a stacking periodicity of 2 unit cells/2 unit cells. The superlattices show drastically different electrical behavior from that of the solid solution (Sr,Ba)TiO3 films. Broad maxima of the dielectric constants occur around 40–50 °C

Dielectric superlattices of (Sr,Ca)TiO3/(Ba,Sr)TiO3 have been formed by a pulsed laser ablation technique. The crystal structure is controlled with atomic order accuracy and a large lattice stress of 0.5–1 GPa can be introduced periodically at the interfaces owing to the lattice mismatch of the constituent layers. The (Sr0.3Ba0.7)TiO3/(Sr0.48Ca0.52)TiO3 superlattice shows dramatically large dielectric constant of 900 even at film thickness of 500 Å. The optimum pressure for inducing tetragonalit

We have formed PbTiO3 thin films on (100) SrTiO3 substrates at a temperature of 350 °C using an ArF excimer laser ablation technique. Until now, PbTiO3 films have not been formed at temperatures lower than 500 °C using other thin-film techniques. The important points in the present study are the laser excitation of the substrate during the film growth and the lattice matching between the film and the substrate. The film deposited on the SrTiO3 substrate shows preferential orientation of the c-ax

Artificial dielectric superlattices of SrTiO 3 /BaTiO 3 (STO/BTO) have been formed by a pulsed laser ablation technique with in situ monitoring of reflection high-energy electron diffraction (RHEED) oscillation. The superlattices with a stacking periodicity of a few unit cells show higher dielectric constant than that of (Sr 0.5 Ba 0.5 )TiO 3 films with change of temperature or applied frequency. The tetragonal structures of the superlattices are maintained at temperatures of more than 200° C ow

To study the initial part of the mouse optokinetic response, OKR (approximately 500 ms from the onset of visual stimulus motion), we recorded the ocular response to a vertical sinusoidal grating moving at a constant velocity. We found that the magnitude of the response monotonically increased as the stimulus contrast increased. The response showed a narrow band-pass property for the spatiotemporal frequency, with the largest sustained response observed at 0.125 cycle/deg and 1.5 Hz. We also foun

Bi-based layered perovskite oxide films ( SrBi 2 Ta 2 O 9 ) have been formed on the Nb-SrTiO 3 substrate or Bi 2 Sr 2 CuO 6 superconducting bottom electrode with c -axis perpendicular to the substrate surface. The dielectric constants of the c -axis oriented SrBi 2 Ta 2 O 9 films deposited on the Nb-SrTiO 3 substrate are as high as 100 and remain constant at an applied frequency from 10 2 to 10 6 Hz. Furthermore, an artificially Bi-based layered perovskite structure can be constructed by the lay