Evidence of Magnetoelectric Coupling in Pb(Fe 0.5 Nb 0.5 )O 3 Ceramics Through Impedance Spectroscopy, Electromechanical
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1161-I03-20
Evidence of Magnetoelectric Coupling in Pb(Fe0.5Nb0.5)O3 Ceramics Through Impedance Spectroscopy, Electromechanical Resonance, and Standard Hysteresis Measurements Oscar Raymond1, Reynaldo Font1,2, Jorge Portelles1,2, Nelson Suárez-Almodovar1,2, and Jesús M. Siqueiros1 1 Centro de Nanociencias y Nanotecnología, UNAM, Ensenada, Baja California, México, 22860. 2 Facultad de Física, Universidad de la Habana, San Lázaro y L, 10400, La Habana, Cuba. ABSTRACT Multifunctional materials such as the single phase compound Pb(Fe0.5Nb0.5)O3 (PFN), where ferroelectric and antiferromagnetic order coexist, are very promising and have great interest from the academic and technological points of view. In this work, coupling of the ferroelectric and magnetic ordering has been observed. For this study, a combination of the small signal response using the impedance spectroscopy technique and the electromechanical resonance method with the large signal response through standard ferroelectric measurement, has been used with and without an applied magnetic field. The measurements to determine the electrical properties of the ceramic were performed as functions of the bias and poling electric ~ fields. A simultaneous analysis of the complex dielectric constant ε~ , impedance Z , electric ~ modulus M , and the electromechanical coupling factors is presented. The results are correlated with a previous study of structural, morphological, small signal dielectric frequency-temperature response, and the ferroelectric hysteretic, magnetic and magnetodielectric behaviors. The observed shifts of the resonance and antiresonance frequency values can be associated with change of the domain size favored by the readjustment of the oxygen octahedron when the magnetic field is applied. From P-E hysteresis loops obtained without and with an external applied magnetic field a maximum value of dc magnetoelectric coefficient αME = 4 kV/cm T (400 mV/cm Oe) was obtained. INTRODUCTION In many ferroelectric compounds with perovskite structure [ A ′A ′′(B′B′′)O 3 ] in which electric and magnetic order coexist, the study of magnetoelectric coupling, understood as the coupling between both orderings where a change in the ferroelectric state or an external electric field induce a change in the magnetic properties, or vice versa, a change in the magnetic order or an external magnetic field induce a change in the electric properties, is very interesting from both the points of view of materials science and technological applications as new devices such as non volatile memory and/or ferroelectromagnetic devices [1-5]. Single phase multiferroic lead iron niobate Pb(Fe0.5Nb0.5)O3 (PFN in reduced notation), is a ferroelectric and antiferromagnetic compound with high dielectric constant where Pb2+ in site A and Nb5+ in site B ′′ favor electrical order and the magnetic moment of Fe3+ in the B′ site is the source of magnetic order. A detailed study of the structural and morphological properties, magnetic measurements, and of the dielectric properties as functions
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