Papers by Author: Takaaki Kuribayashi

Abstract: We investigated the magnetic interaction between antiferromagnetic, magnetoelectric Cr2O3 film and ferromagnetic La0.7Sr0.3MnO3 film, which shows colossal magneto-resistance. Magnetic properties and structural analyses revealed that a decrease in the thickness of La0.7Sr0.3MnO3 films gives rise to a change in magnetic anisotropy from perpendicular to in-plane. The exchange interaction between Cr2O3 and La0.7Sr0.3MnO3 also changed depending on the magnetic properties of La0.7Sr0.3MnO3. This suggests that the crystallographical control and the selection of a suitable thickness of La0.7Sr0.3MnO3 are important to obtain an exchange interaction in the magnetic hetero system using colossal magneto-resistance material.

Abstract: We investigated the magnetic and dielectric properties of a metal (Pt)/insulator (Cr2O3)/semiconductor (Si) (MIS) capacitor composed of magneto-electric (ME) materials. The capacitor has anti-ferromagnetic properties and a very small electrically induced magnetic moment. It also shows capacitance-voltage (C-V) properties typical of a Si-MIS capacitor without any hysteresis. By inserting a thin Cr2O3-x layer, the C-V curve has a hysteresis window with a clockwise trace, which indicates that electrons have been injected into the Cr2O3-x layer. These results indicate that this MIS capacitor contains a floating gate and an ME insulating layer in a single system.

Abstract: We investigated the magneto-electric properties and electric properties of Cr2O3 thin films. Cr2O3 thin films were prepared on a thermal-oxidized Si substrate and a c-Al2O3 substrate. The sample prepared on the thermal-oxidized Si substrate had poly-crystalline structure. On the other hand, the sample prepared on the c-Al2O3 substrate has preferentially (006) oriented structure. Both samples had high enough resistivity to get a high induced magnetic moment. The induced magnetic moment by applying external voltage was observed on the oriented sample, although there was no induced magnetic moment on the same voltage for the poly-crystalline sample. This difference may be due to the random distribution of crystal and the leakage current caused by the Pool-Frenkel type defect in the poly-crystalline film.