Measurement of dynamic magnetization reversal of magnetic film fabricated onto BiFeO3 based multiferroic film by applying electric field and development of the multiferroic film with high magnetization for this method

Abstract

The Measurement of dynamic magnetization reversal of ferromagnetic [Co/Pd] film dot fabricated onto highly-qualified (Bi,La)(Fe,Co)O3 multiferroic film by applying an electric field to this laminated film was tried. The magnetization of (Bi,La)(Fe,Co)O3 film will be switched by applying the electric field. Therefore, the magnetization switching of [Co/Pd] film dot will be performed by magnetization switching of (Bi,La)(Fe,Co)O3 film via magnetic interaction. To measure the dynamic magnetization reversal of [Co/Pd] film dot, I developed a new “magneto-electric effect (MEE)” measurement system which is combining magneto-optical Kerr effect (MOKE) measurement equipment and ferroelectric tester. The hysteresis of MOKE against electric field with 1 kHz was measured by this MEE measurement system. This indicate that the magnetization direction of [Co/Pd] film dot was changed by “magnetization transfer by applying the electric field” via magnetic interaction from magnetization of (Bi,La)(Fe,Co)O3 film. However, the hysteresis loop was not clear with low signal and high noise. To get clear hysteresis loop, development of BiFeO3-based multiferroic film with very high magnetization is necessary. I investigated the substitution of Lanthanoid and Alkaline earth against Bi, and substitution of Co against Fe for BiFeO3. I succeeded the fabrication of (Bi,Nd)(Fe,Co)O3 film with the saturation magnetization of 140 emu/cm3 which is two times larger than the case of (Bi,La)(Fe,Co)O3 film. And this (Bi,Nd)(Fe,Co)O3 film showed clear perpendicular anisotropy, which is very important for magnetic device application. This results indicates that the almost complete magnetization switching of magnetic film fabricated onto (Bi,Nd)(Fe,Co)O3 film will be realized by “magnetization transfer by applying the electric field”, and this method will make magnetic device with low power consumption.