Fabrication and characterization of artificially designed PZT/LSMO multiferroics heterostructure
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Fabrication and characterization of artificially designed PZT/LSMO multiferroics heterostructure Sandra Dussan, Ashok Kumar and Ram S. Katiyar* Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931-3343, USA. E-mail :(*) [email protected] ABSTRACT Highly oriented and epitaxial bilayers of PbZr0.52Ti0.48O3/La0.67Sr0.33MnO3 (PZT/LSMO) thin films were grown by pulsed laser deposition technique on two different substrates (100) - MgO and -LaAlO3 (LAO) respectively. The structural analysis using X-ray diffraction (XRD) evidenced that layered structure was formed without any secondary phase. Atomic force microscopy (AFM) images shown change in the grain size and surface roughness with change of the substrate and growth temperature. Room temperature magnetization-field (M-H) exhibited well-shaped magnetization hysteresis loops, good saturation and low coercivity. The electrical properties of hetrostructure exhibited high remnant polarization (30-54 µC/cm2) and dielectric constant (400-1700) depending upon the different substrate and deposition temperature of ferromagnetic (FM) layer. Frequency dependent change in dielectric constant and loss were observed above metallic ferromagnet to insulator paramagnet transition temperature. It is important to note that the frequency dependent dielectric anomalies are attributed to the change in metallic nature of LSMO bottom electrode. INTRODUCTION Multiferroic materials are a class of functional materials that combine two or more functional properties i.e. ferromagnetism, ferroelectricity and ferroelasticity.1,2 Simultaneous existence of ferroelectric and ferromagnetic properties in the same material have attracted scientific and technological interest in the last decade due its potential applications in magnetic data storage, sensors, non-volatiles memories, actuators, micromechanical applications, and the emerging field of spintronics.3,4 Several ferromagnetic-ferroelastic (magnetostricve) and ferroelectricferroelastic (piezoelectric) materials are known, but very few multiferroic single-phase material exist in nature, which derives from the fact that the two properties are chemically incompatible; i.e. the existence of transition metal d-electrons are essential for ferromagnetism, disfavor the tendency of the off-center displacement of cations that cause ferroelectricity.5 Alternative mechanisms to obtaine both electrical and magnetic ordering in a single phase material have been the construction of artificially multiferroics thin films combining a ferroelectric and a ferromagnetic material.6 The perovskite PbZrxTi1-xO3 (PZT)-layer as a constituent of heterostructure have been used owing to its high remanent polarization (Pr) low coercive field (Ec) and high Curie temperature.7 Moreover LaxSr1-xMnO3 is in an interesting candidate not only as a ferromagnetic-layer element in the heterostructures but also as a botton electrode for ferroelectric films due to high curie temperature ~340 K and its la
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