Effect of Processing Conditions on Electrical and Magnetic Properties of Pb(Zr, Ti)O 3 CoFe 2 O 4 Multilayers Thin Films
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1000-L06-23
Effect of Processing Conditions on Electrical and Magnetic Properties of Pb(Zr,Ti)O3 CoFe2O4 Multilayers Thin Films Nora Patricia Ortega1, P. Bhattacharya2, Ram S Katiyar1, S B Majumder3, I Takeuchi4, P. Dutta5, M S Sheehra5, and Ashok Kumar1 1 Department of Physics, University of Puerto Rico, PO Box 23343, San Juan, 00931-3343, Puerto Rico 2 Department of Physics, Fisk University, Nashville, TN, 37208 3 Materials Science Center, Indian Institute of Technology, Kharagpur, 721302, India 4 Department of Materials, University of Maryland, College Park, MD, 20742 5 Department of Physics, West Virginia University, Morgantown, WV, 26506 The multilayers of ferroelectric (FE) Pb(Zr,Ti)O3 (PZT) and ferromagnetic (FM) CoFe2O4 (CFO) thin films with 3, 5, and 9 layers having configurations PZT/CFO (PC) and CFO/PZT (CP) were fabricated by pulsed laser deposition technique. We have investigated the effect of inter-diffusion at the interface of multilayers (MLs) and reversing the order of FE and FM layers in the multilayers configuration on the electrical/magnetic properties. The TEM of the films showed that the layer structure was not maintained and the inter-diffusion of the CFO into PZT and vice verse were observed at the interface of MLs. Both the PC and CP configurations of multilayer films exhibited pseudo FE hysteresis loop and proper FM hysteresis loops at room temperature. Reversing the multilayer configuration from CP to PC resulted in increasing the pseudo remanent polarization, however this behavior was not observed in magnetic properties. The frequency and temperature dependences of the impedance and modulus spectroscopy of the multilayer PC and CP films were studied in the ranges of 102 to 106 Hz and 200 to 650 K respectively. The electrical response of all multilayer films investigated could be resolved into two contributions. We attributed these to the grain and grain boundary effects in impedance and modulus formalism. We found that the difference between the grain and grain boundary capacitive effect decreased due to increase of the number of layers. INTRODUCTION Recently, considerable attention has been focused on multiferroic materials due to their multifunctionality that could lead to potential applications in highly sensitive actuators and sensors as well as multi-state memory devices. These multiferroic materials are characterized by their magnetic as well as electrical polarization ordering and the coupling between these two order parameters [1]. Several efforts have been made to synthesize magnetoelectric (ME) composite thin films with coexisting ferroelectric (FE) and ferromagnetic (FM) properties, for the next generation miniaturized integrated devices. Different configurations were reported for fabrication of ME composite thin films, such as composite spreads with terminal layers being FE and FM [2], double Pb(Zr,Ti)O3 (PZT)/CoFe2O4 (CFO) multilayers [3], superlattices consisting of alternating FM (Pr0.88Ca0.15MnO3)and FE (Ba0.6Sr0.4TiO3)layers deposited on SrTiO3 [4], epitaxial CoFe2O4-BaT
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