© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.pss-rapid.com pss Phys. Status Solidi RRL 5, No. 10 – 11, 391 – 393 (2011) / DOI 10.1002/pssr.201105357 Strong magnetoelectric coupling in highly oriented ZnO films deposited on Metglas substrates Ravindranath Viswan * , David Gray, Yaojin Wang, Yanxi Li, David Berry, Jiefang Li, and D. Viehland Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061, USA Received 20 July 2011, revised 30 August 2011, accepted 13 September 2011 Published online 16 September 2011 Keywords magnetoelectric effect, piezoelectric materials, magnetostriction, thin films * Corresponding author: e-mail ravi25@vt.edu, Phone: +01 540 577 1681, Fax: +01 540 231 8919 © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Magnetoelectric (ME) coupling which manifests as a change in the electric polarization with application of a magnetic field, or as a change in the magnetization with application of an electric field, has been extensively stud- ied because of its potential in a variety of applications such as magnetic sensors, non-volatile magnetic memories and other multifunctional devices [1 – 3]. For practical applica- tions where miniaturization of devices becomes important, the study of ME effects in thin film composites becomes inevitable. Although, the fabrication and characterization of a number of multilayered and self-assembled ME com- posite thin films has been reported [1, 2], there are very few reports of the measurement of dynamic ME effects in these thin films [4, 5]. This is primarily because of the fact that the ME voltage that is generated in the thin film het- erostructures is usually of the order of a few μV or less [6]. One reason for this is that in thin film heterostructures, the substrate imposed mechanical clamping suppresses the strain mediated ME coupling, especially in the 2 – 2 type layered heterostructures due to a large in-plane constraint [7]. In order to overcome the problem of substrate clamp- ing, several researchers have studied thin film heterostruc- tures deposited on substrates with reduced thicknesses [4, 5], or by the deposition of magnetostrictive films on piezo- electric substrates [8]. However, the study of magnetoelec- tric coupling in piezoelectric thin films deposited on mag- netostrictive substrates remains largely unexplored because of the high temperature necessary to deposit oriented pie- zoelectric thin films. At such high temperatures, the prop- erties of magnetostrictive substrates degrade considerably [9]. In this context, the low temperature growth of ZnO films on Metglas substrates was studied. Undoped ZnO is a piezoelectric material with a piezoelectric voltage coeffi- cient of about 10 pm/V [10]. Recently, Cu-doped ZnO was reported to possess multiferroic properties with a ME coef- ficient of 1.2 mV/cm Oe at a frequency of 600 Hz [11]. However, there have been no reports of ME coupling in bulk composites or thin film heterostructures of undoped ZnO. In this paper, we report strong ME coupling in highly oriented ZnO films deposited on Metglas substrates. This is the first report of dynamic converse and direct ME measurements in a semi-monolithic heterostructure. Thin films of ZnO were deposited on 25 μm thick Metglas ® foils (VITROVAC7600F, nominal composi- tion: Fe 74.4 Co 21.6 Si 0.5 B 3.3 Mn 0.1 C 0.1 ) obtained from Vacuum- schmelze (Germany) by pulsed laser deposition (PLD) at a low substrate temperature of 300 °C. The films were de- posited using a Lambda 305i KrF laser with a wavelength of 248 nm, focussed to a spot size of 1.2 mm 2 , and incident We have studied the magnetoelectric coupling in ZnO films deposited on Metglas substrates. Highly c-axis oriented ZnO films were successfully deposited using pulsed laser deposi- tion at a low temperature of 300 °C. High quality films with low surface roughness of 2.82 nm and thicknesses of about 2 μm were obtained. A large converse magnetoelectric coef- ficient of 3 × 10 –6 s/m and a direct magnetoelectric coefficient of 47 mV/cm Oe at a low dc bias field of 17 Oe and fre- quency of 1 kHz were obtained by dynamic converse and di- rect magnetoelectric measurements, respectively. Our results demonstrate a significant magnetoelectric coupling in these layers.