Development of Ferroelectric & Ferromagnetic Thin Film

[目的]最近，Fujii et al.1)报道了Bi_2O_3-Fe_2O_3-ABO_3(AB=PbTi，BaTi.等)射频反应溅射制备的薄膜由非晶相组成，在873-973K的空气中热处理后具有较大的饱和磁化强度和较高的透过率。然而，高介电性还没有报道，关于该体系的磁光性质的报道也很少。其次是铅(0.53&gt；Ti_&lt；0.47&gt；本研究选用)O_3(PZT)作为ABO_3，研究了这些薄膜的电学、磁(磁)光和光学性能。[实验方法]所研究的薄膜的组成为：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).这些薄膜是用射频溅射方法制备的。热处理温度为573-973K，用VSM测量磁性能，用克尔回线示踪仪测量电性能，用LCR仪测量电性能。[结果](1)经973K热处理的0.5BiFeO_3-0.5PZT薄膜的饱和磁化强度为21.6MWBM^~(-2)，介电常数为548，在633 nm处的透过率为77%。(2)从X射线衍射谱可以看出，在948K以下，0.625Fe_3O_3-0.375{0.33(Bi_&lt；1-x&gt；La_x)_2O_3-0.67PZT}(x=0.3)薄膜由非晶相组成。(3)获得了饱和磁化强度ms=57.3mWbm^~(-2)、矫顽力Hc=183kAm^~(-1)~(-1)、方度MR/ms=0.64的磁特性。(4)该薄膜在633 nm处也表现出2Rheta_k=0.52 deg的假Kerr旋光。从电子显微镜观察到，尽管电子衍射图上有晕环图案，但薄膜中可观察到超细的颗粒团聚现象，似乎该薄膜的磁化起源与这些团聚有关。

[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.