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Abstract: Perovskite bismuth ferrite (BiFeO3) layer, which is widely recognized as a multiferroic material, was prepared on a c-axis-oriented strontium ferrite (SrFe12O19) layer by magnetron sputtering to form a BiFeO3/SrFe12O19 bilayer. Direct observations of the magnetic and electric domains originating from the magnetism coincident with the ferroelectricity of BiFeO3 in the bilayer were achieved through magnetic force microscopy and electrostatic force microscopy, respectively. Simultaneous existence of magnetic and electric domains was observed in the BiFeO3 phase. A pinning effect of BiFeO3 in relation to SrFe12O19 was suggested from the magnetic hysteresis curves, although BiFeO3 layer exhibits a small magnetization. By applying a magnetic field to the BiFeO3/SrFe12O19 bilayer, the electric domains in the BiFeO3 layer sensitively respond, which implies that ferroelectric polarization in BiFeO3 layer can be magnetically controlled. [Copyright &y& Elsevier]

Abstract: Strontium ferrite (SrM) thin films were prepared by dc magnetron sputtering system on thermally oxidized silicon wafer (SiO2/Si), single-crystal sapphire with (00l) orientation and single-crystal MgO with (111) orientation and the effect of Au and Pt underlayers on morphology and magnetic properties was studied. Experimental results revealed that with the application of underlayers, the crystallization temperature of SrM was reduced. Strontium ferrite thin films with uniaxial anisotropy were formed on all substrate specimens. Comparison of the results obtained on all thin films indicated that the maximum saturation magnetization and coercivity in the perpendicular direction were 0.377T and 0.382MAm−1, respectively, for thin films with Au underlayer and SiO2/Si substrate. [ABSTRACT FROM AUTHOR]

Abstract: Strontium ferrite (SrM) thin films were deposited on thermally oxidized silicon wafer with Au underlayer. Gold underlayers were prepared at various substrate temperatures by using a magnetron sputtering system. C-axis oriented SrM perpendicular films and preferred (111) orientation of underlayer have confirmed by X-ray diffraction patterns. The intensity of (111) diffraction line for Au and that of (00 l) diffraction line for strontium ferrite decrease with increase in substrate temperature (T u) The maximum coercivity and remanent squareness ratio in perpendicular direction, at T u of 500°C, are 5.4kOe and 0.68, respectively. The strength of the intergranular interaction of SrM magnetic particles is described by the parameter Δm. The SrM/Au films prepared at T u above 100°C have smaller Δm peak values than that for SrM/Au films prepared at T u of room temperature. This behavior is related to low magnetostatic coupling between the magnetic particles separated by the non-magnetic amorphous phase. [Copyright &y& Elsevier]