BiFeO₃ based thin films with ferromagnetism were fabricated by using a pulsed DC reactive sputtering method. Guidelines on sputtering targets for fabricating the films are discussed in regard to obtaining high-quality BiFeO₃ based thin films. By using a target with a low oxide content (low molar ratio of oxide) and thus good conductivity, it is possible to suppress the charging and arc discharge on the surface of the target and enable high-energy sputtering. As a result, high-quality BiFeO₃ based thin films with a high saturation magnetization were formed. By using a target with a high oxygen content (including oxides with a high oxidation valence), the generation of oxygen vacancies that degrade the ferroelectric properties is suppressed, and pinning sites that suppress domain wall movement are then also suppressed. As a result, high-quality BiFeO₃ based thin films with good ferromagnetic properties could be formed.

  Research on non-contact transport technology is being carried out in order to apply magnetic levitation technology using electromagnets to the transport systems used in production lines for thin steel plates. When an ultrathin and flexible steel plate is to be levitated, levitation control becomes difficult due to the flexure of such a plate. Therefore, we previously proposed a bending levitation system in which an ultrathin steel plate is bent to an extent that does not induce plastic deformation. However, in an actual usage environment, there are electrical noise and mechanical disturbances, which deteriorate the levitation performance. To investigate the levitation stability of an ultrathin steel plate in this case, we applied sliding mode control in the bending levitation system. Sliding mode control theory is a robust control theory that hardly deteriorates the control performance even in the presence of modeling errors and disturbances. We conducted experiments on levitation performance with an electromagnet that was vibrated in the vertical direction. The results show that stable levitation can be realized even with input external disturbance when the steel plate is levitated at the optimum bending angle.