Magnetoelectric properties of BST/LSMO particulate composites
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Magnetoelectric properties of BST/LSMO particulate composites Juan Beltran-Huarac, R. Martinez, and R. Palai Department of Physics, University of Puerto Rico, San Juan, PR 00931, USA ABSTRACT Currently, ferroelectric and ferromagnetic particulate composites are receiving a great deal of interest due to their novel applications in microelectronic devices. Their excellent properties such as high relative dielectric constant, low dielectric loss, strong tunability, and ferromagnetism with colossal magnetoresistance can be controlled by manipulating both electric and magnetic fields. Ba0.7Sr0.3TiO3 /La0.67Sr0.33MnO3 (BST/LSMO) composite was prepared with 20:1 wt% by a high temperature solid-state reaction route. The X-ray diffraction (XRD) pattern confirmed the formation and the coexistence of both phases corresponding to BST and LSMO. High resolution field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) revealed a uniform distribution of the grain size throughout the surface of the sample and the presence of all the constituent elements with its esteemed reaction stoichiometry, respectively. In spite of the presence of both phases, only one transition peak was seen (50Hz-5MHz) around 295 K in dielectric measurement suggesting a nonlinear magnetoelectric coupling. The dielectric properties of BST/LSMO composite carried with different magnetic fields (0-1.7 T) show significant change in the BST dielectric behavior at low frequencies. The M-H curves at room temperature (RT) showed a drop in the saturation magnetization compared with pure LSMO is consistent with our composite structures. INTRODUCTION Research on multiferroic materials is emerging with increased interest because of the coexistence of at least two ferroic orders in the same phase that can lead to novel magnetoelectric or magnetodielectric coupling in addition to the single-phase interactions [1]. For instance, the change in the dielectric constant and switching in the polarization by magnetic field will offer a vital insight into origin of spin-charge coupling. It is also know that the magnetization of the material can be also changed by the application of electric field [2, 3]. However, multiferroic materials are very limited and it is very rare at RT because of the mutual exclusive requirements, e.g., empty d-shell for ferroelectricity and partial filled for ferromagnetism [1, 3, 4]. BiFeO3 is the only known RT multiferroic (ferroelectric and antiferromagnetic) with many interesting physical properties [5-8], but it is high leakage current is the bottleneck for device applications [9]. In the present work, we combined RT ferroelectric and ferromagnetic materials to have artificial multiferroic materials. Barium strontium titanate, Ba0.7Sr0.3TiO3 (BST), is an important ferroelectric material owing to its high relative dielectric constant, low leakage current and good performance near the room temperature [10]. It possesses a tetragonal structure with a=3.959Å and c=3.967Å and TC=312K [11]. Whereas, lanthanum str
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