Development of Ferroelectric & Ferromagnetic Thin Film

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[Purpose] Recently, Fujii et al. 1) reported that the Bi_2O_3-Fe_2O_3-ABO_3 (AB=PbTi, BaTietc.) thin films prepared by rf-reactive sputtering consist of an amorphous phase, and exhibit large saturation magnetization and high transmittance after annealing at 873-973K in air. However, high diellectricity has not been reported and there are few reports about magneto-optical properties of this system. Then the Pb (Zr_<0.53>Ti_<0.47>) O_3 (PZT) were chosen for ABO_3 in this study, and electric, magnetic (magneto-optical)and optical properties of these films were studied.[Experimental Procedure] The compositions of studied fulms are x(0.5Bi_2O_3-0.5Fe_2O_3)-(1-x) PZT (x=0.2,0.4,0.5,0.6,0.8,1.0), xFe_2O_3-(1-x)(0.33Bi_2O_3-0.67PZT)(x=0.25,0.375,0.50,0.625,0.75,0.875), yFe_2O_3-(1-y)(0.54Bi_2O_3-0.46PZT)(y=0.35,0.475,0.60,0.725,0.85), zFe_2O_3-(1-z)(082Bi_2O_3-0.18PZT)(z=0.45,0.575,0.70,0.825). These films were prepared by RF sputtering. The heat treat ment were done at 573-973K.Magnetic properties were measured by VSM,Kerr loop tracer and electric properties were measured by LCR meter. Microstrucutre was observed by TEM.[Results] (1) 0.5BiFeO_3-0.5PZT film annealed at 973K exhibits saturation magnetization of 21.6m Wbm^<-2>, dielectricity of 548 and transmittance of 77% at 633nm. (2) From XRD patterns, 0.625Fe_3O_3-0.375{0.33(Bi_<1-x>La_x)_2O_3-0.67PZT}(x=0.3) films at the temperatures below 948K consist of an amorphous phase. (3) Magnetic properties of saturation magnetization Ms=57.3mWbm^<-2>, coercive force Hc=183kAm^<-1>, and squarness Mr/Ms=0.64, were obtained in this film.. (4) This film also exhibits a false Kerr rotation of 2 rheta_k=0.52deg at the wavelength of 633nm. From the TEM observations, ultrafine agglomeration of particles can be observed in this film, in spite of halo pattern in the electron diffraction patterns.it seems that the origin of magnetization of this film is related to these agglomerations.