Development of Ferroelectric & Ferromagnetic Thin Film

【目的】最近，Fujii et al. 1)报道了采用rf反应溅射法制备的Bi_2O_3-Fe_2O_3-ABO_3 （AB=PbTi， bati3等）薄膜由非晶态相组成，在873-973K空气中退火后表现出较大的饱和磁化强度和高透射率。然而，高介电性尚未见报道，关于该体系磁光特性的报道也很少。然后选择Pb (Zr_<0.53>Ti_<0.47>) O_3 （PZT）作为ABO_3薄膜，研究了这些薄膜的电、磁（磁光）和光学性能。(实验过程)的成分研究fulms x (0.5 bi_2o_3 - 0.5 fe_2o_3) - (1 - x)压电陶瓷(x = 0.2, 0.4, 0.5, 0.6, 0.8, 1.0), xFe_2O_3 - (1 - x) (0.33 bi_2o_3 - 0.67 -钛酸(x = 0.25, 0.375, 0.50, 0.625, 0.75, 0.875), yFe_2O_3 - (1 y) (0.54 bi_2o_3 - 0.46 -钛酸(y = 0.35, 0.475, 0.60, 0.725, 0.85), zFe_2O_3 - (1 - z) (082 bi_2o_3 - 0.18 -钛酸(z = 0.45, 0.575, 0.70, 0.825)。这些薄膜是通过射频溅射制备的。热处理温度为573 ~ 973k。磁性能采用VSM法测定，克尔环示踪剂测定，电性能采用LCR仪测定。用透射电镜观察了显微组织。[结果](1)在973K下退火的0.5BiFeO_3-0.5PZT薄膜在633nm处的饱和磁化强度为21.6m Wbm^<-2>，介电系数为548，透过率为77%。(2) XRD谱图表明，在948K以下的温度下，0.625Fe_3O_3-0.375{0.33(Bi_<1-x>La_x)_2O_3-0.67PZT}（x=0.3）薄膜为非晶相。(3)获得饱和磁化强度Ms=57.3mWbm^<-2>，矫顽力Hc=183kAm^<-1>，方尺Mr/Ms=0.64的磁性能。(4)在633nm波长处，该薄膜还表现出2 rheta_k=0.52°的假Kerr旋转。透射电镜观察发现，薄膜中存在超细颗粒团聚现象，但在电子衍射图中存在晕纹。这种薄膜的磁化来源似乎与这些团块有关。

[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.