Multiferroic BiFeO 3 /BaTiO 3 thin films fabricated by chemical solution deposition technique
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Multiferroic BiFeO3/BaTiO3 thin films fabricated by chemical solution deposition technique Savita Sharma1,3, Monika Tomar2, Ashok Kumar4, Nitin K. Puri3 and Vinay Gupta1* 1 Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India 2 Physics Department, Miranda House, University of Delhi, Delhi 110007, India 3 Department of Applied Physics, Delhi Technological University, Delhi 110042, India 4 CSIR-National Physical Laboratory, Dr. K.S .Krishnan Marg, New Delhi-110012, India E-mail Id : [email protected], *[email protected] Contact No. : +91 9811563101 ABSTRACT The BiFeO3/BaTiO3 (BFO/BTO) multilayers were deposited on Pt/Ti/SiO2/Si substrates using sol-gel spin coating technique. The electric and magnetic studies on BFO/BTO multilayer structures were carried out for different number of layers. Enhancement in multiferroic properties were seen for all the prepared multilayers as compared to individual BTO and BFO thin films. Maximum value of ferroelectric polarization 71.18 µC/cm2 and saturation magnetization 69.85 emu/cm3 was obtained for multilayer structure having five layers. The observed enhancement in the multiferroic properties of the multilayer system is due to the increased interfacial stress and multiferroic coupling between the alternating layers. INTRODUCTION Multiferroic materials have attracted considerable attention due to the coexistence of magnetic and electric properties giving potential applications in sensors and actuators, spintronic devices and memory devices [1-2]. Bismuth ferrite, BiFeO3 (BFO), with rhombohedrally distorted structure, is the only perovskite material which is multiferroic at room temperature [3]. Recently BFO has attracted significant attention not only for the fundamental research but for potential practical applications as well such as magnetoelectric devices, spintronics and ferroelectric random access memory etc [1-2]. However, BFO exihibits a large leakage current density leading to high electrical conductivity and hence poor ferroelectric property [4]. Barium titanate, BaTiO3 (BTO), lead free typical perovskite having high dielectric constant exhibits excellent ferroelectric properties and large electro-optic coefficient. BTO has received much attention since last many decades due to its wide applications in dynamic random access memories (DRAMs), pyroelectric detectors, multilayer ceramic capacitors (MLCC) etc. [5-6]. There have been voluminous studies dedicated towards the reduction of leakage current in BFO using A-site or B-site doping and enhancing its ferroelectric properties [7]. In last few years, interest has been developed among researchers towards the heterogeneous multilayer structure having alternating perovskite and ferrite layers which can have enhanced dielectric and ferroelectric properties with reduced leakage current [8]. Designing of materials having enhanced magnetoelectric responses can be achieved using the principles of strain engineering employed to multilayer films and superlattices (SLs). In this light, recent study
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