Effects of exchange interactions on magnetoacoustic resonance in layered nanocomposites of yttrium iron garnet and lead
- PDF / 193,479 Bytes
- 5 Pages / 585 x 783 pts Page_size
- 40 Downloads / 251 Views
V.M. Petrov and G. Srinivasana) Physics Department, Oakland University, Rochester, Michigan 48309 (Received 17 December 2006; accepted 16 May 2007 )
In ferrite–piezoelectric bilayers, the magnetoelectric (ME) interaction is mediated by mechanical strain. The ME coupling is expected to be strong, particularly when the magnetic and electric subsystems show resonance. Here we address the effect of magnetic exchange interactions on ME coupling at magnetoacoustic resonance (MAR), i.e., at the coincidence of electromechanical resonance in the piezoelectric phase and ferromagnetic resonance in a tangentially magnetized ferrite. When exchange is ignored, the estimated ME coefficient versus frequency profile shows a giant magnetoelectric coefficient at MAR, about 75–100 V/cm Oe for yttrium–iron garnet (YIG)/lead zirconate–titanate (PZT) nano bilayers. The magnetic exchange is predicted to enhance the coupling at MAR and produce a secondary peak due to the excitation of magnetoacoustic modes. Estimates of the ME coefficient are provided as a function of thickness ratio of YIG and PZT.
I. INTRODUCTION
The magnetoelectric (ME) interactions in laminated ferrite–piezoelectric bilayers are due to mechanical interactions between the magnetic and electric subsystems.1 The magnetostriction of the ferrite in an external magnetic field causes polarization of piezoelectric phase. One ME phenomenon of both fundamental and technological interest is the coupling when the electrical or magnetic subsystem shows a resonant behavior, i.e., electromechanical resonance (EMR) for lead zirconate–titanate (PZT) and ferromagnetic resonance (FMR) for the ferrite.2–6 The resonance ME effect at EMR is similar in nature to the standard effect, i.e., an induced polarization under the action of an ac magnetic field. But the alternating current (ac) field here is tuned to the electromechanical resonance frequency. As the dynamic magnetostriction is responsible for the electromagnetic coupling, EMR leads to significant increasing in the ME voltage coefficients.5,6 A 2- to 3-order of magnitude increase in ␣E at EMR was measured compared to low-frequency values. We developed the theory for ME coupling at EMR at radial and thickness modes for a ferromagnetic/
a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2007.0275 2174 J. Mater. Res., Vol. 22, No. 8, Aug 2007 http://journals.cambridge.org Downloaded: 16 Mar 2015
piezoelectric bilayer.5 We reported the first observation of these effects and provided theoretical models.5 We made the first measurements of microwave ME interactions through FMR in bilayers of single crystal ferromagnetic–piezoelectric oxides.7 An electric field E produces a mechanical deformation in the piezoelectric phase, resulting in a shift in the resonance field for the ferromagnet. The strength of ME coupling was obtained from data on shift versus E. Studies were performed on bilayers of yttrium iron garnet (YIG) films and (001) lead magnesium niobate/lead titanate (PMN-PT) or PZT. We also
Data Loading...
