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Thickness dependendence of the magnetoelectric coupling in FeGa thin films deposited on PMN-PT single crystalsMaría Julia Jiménez1, Javier E. Gómez2, Daniel Velásquez Rodriguez2, Livio Leiva3,Julián Milano4, Alejandro Butera41 Dpto. de Física, Universidad Nacional del Sur, Bahía Blanca, Argentina.2 Centro Atómico Bariloche. Comisión Nacional de Energía Atómica (CNEA). Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Av. Bustillo 9500, 8400 Bariloche, Río Negro, Argentina.3 Centro Atómico Bariloche e Instituto Balseiro. Comisión Nacional de Energía Atómica (CNEA). Universidad Nacional de Cuyo (UNCUYO). Av. Bustillo 9500, 8400 Bariloche, Río Negro, Argentina.4 Centro Atómico Bariloche and Instituto Balseiro. Comisión Nacional de Energía Atómica (CNEA). Consejo Nacional de Investigaciones Cientí cas y Técnicas (CONICET). Universidad Nacional de Cuyo (UNCUYO).Av. Bustillo 9500, 8400 Bariloche, Río Negro, Argentina.E-mail (autor que presentará el trabajo): butera@cab.cnea.gov.arStraintronics have recently emerged as an alternative for ultra low power switching ofmagnetic nanoelements in storage devices.[1] The magnetization of small elements can berotated, or even switched, when they are grown on top of a piezoelectric layer that can bedeformed with the application of a relatively small voltage.[2] The voltage is applied on thetop and bottom faces of the piezoelectric (PE) material that deforms anisotropically andinduces a change in the easy axis of magnetization of the ferromagnet (FM) via the inversemagneostrictive effect. Several different materials have been proposed and used for theferromagnetic and piezolectric components,[3] and, as a general rule to obtain a largemagnetoelectric effect, the FM should have a high magnetostriction constant and the PE alarge piezoelectric coefficient.We have investigated the effects of applying an electric field on the dc and ac magneticresponse of FeGa thin films (t=6, 11, 17, 22, and 28 nm) that have been deposited onferroelectric PMN-PT [011] and [001] single crystals.Upon the application of an electric field we have observed that M vs. H hysteresis loops aremodified in films grown on [011] crystals, consistent with a negative magnetostrictionconstant that depends on film thickness. Samples deposited on [001] substrates, on the otherhand, show a very weak dependence on thickness with electric field.Ferromagnetic resonance experiments at 9.5 GHz were performed in order to estimate themagnetostriction constant and to obtain the magnetoelectric coefficient as a function ofthickness. We have observed that in the case of [011] substrates the magnetostrictionconstant depends on film thickness and has relative maxima for t=6 and 28 nm. Themagnetoelectric coefficient shows a similar dependence on film thickness, confirming thatthe main effect is due to magnetoelastic anisotropy.In the case of 28 nm films deposited on PMN-PT [011] it was found that the direction of easymagnetization could be rotated by 90º upon the application of an electric field.These results indicate that if magnetostrictive materials are to be applied in straintronicdevices the dependence of magnetic parameters with film thickness must be taken inaccount for optimum performance.[1] K. Roy, S. Bandyopadhyay, and J. Atulasimha. Appl. Phys. Lett. 99, 063108 (2011).[2] A. K. Biswas, H. Ahmad, J. Atulasimha, and S. Bandyopadhyay. Nano Lett., 17, 3478(2017).[3] Cheng Song, Bin Cui, Fan Li, Xiangjun Zhou, Feng Pan. Progress in Materials Science,87, 33. (2017)