Optimizing direct magnetoelectric coupling in Pb(Zr,Ti)O3/Ni multiferroic film heterostructures

Abstract

Polycrystalline Pt thin films of different thicknesses (0–75 nm) were introduced using magnetron sputtering in Pb(Zr0.52Ti0.48)O3 (PZT, 400 nm in thickness)/Pt/Ni multiferroic film heterostructures, aimed at optimizing the transfer efficiency of magnetostrictive strain from the bottom Ni foil to the top PZT film and thus the direct magnetoelectric (ME) coupling. The ME voltage coefficient αE31 was directly measured, while the strain transfer efficiency k was obtained by combined experimental and theoretical analysis. At the optimum Pt-thickness of 30 nm, the polycrystalline film heterostructure shows the largest αE31 of 772 mV cm−1 Oe−1 at a low dc magnetic bias field of 86 Oe, as well as the highest k of 83% that is comparable to that in epitaxial quasi-2-2 film heterostructures.

Tailoring the Magnetoelectric Properties of Pb(Zr,Ti)O3 Film Deposited on Amorphous Metglas Foil by Laser Annealing

“…For comparison, the maximum value of ME coefficient obtained herein is about an order of magnitude higher than that (43 mV/cm·Oe at H dc = 134 Oe) reported by Wang et al for a 2.1 μm thick PZT film deposited on Metglas foil. Our ME coefficient value is also comparable to some of the best reported α ME for PZT‐based ME film composites …”

A flexible, high-performance magnetoelectric heterostructure of (001) oriented Pb(Zr0.52Ti0.48)O3film grown on Ni foil

“…Although some previous studies have reported the development of PZT/Ni film-based ME composites, it has been challenging to achieve an appreciable ME output. [13][14][15] This can be attributed to the processing issues raised by the thermodynamic incompatibility between PZT and Ni. If no passivation layers are utilized during PZT film crystallization, the high temperatures required cause oxidation of Ni and interfacial chemical reactions between PZT and Ni; these complicate the strain transfer and impair the ME coupling.…”

“…A comparison of the α ME values of various reported ME composites relevant to this work is shown in Table S1 of the supplementary material. [13][14][15][24][25][26][27]30 The α ME obtained from the (001) oriented PZT film on the Ni foil significantly outperforms that of all the ME film composites based on either PZT/Ni or textured PZT films deposited on magnetostrictive oxide substrates. The high piezoelectric response and the low dielectric constant, due to the strong texturing of the PZT grains and their domain state, presumably contributed to the larger ME output, since α ME ∝ g ij (=d ij /ε ij ), where ε ij is dielectric permittivity and g ij and d ij are piezoelectric voltage and charge coefficients, respectively.…”

“…15 Feng et al observed α ME of 0.772 V/cm·Oe in the PZT/Pt/Ni multiferroic film heterostructure at an optimum Pt-thickness of 30 nm. 14 Kambale et al reported α ME of 1 V/cm·Oe in a PZT film deposited on Ni with an LNO buffer layer between them. 13 Comparison of the measured α ME values of PZT/Ni film composites with the ideally obtainable ones suggest that there is room for improvement in ME coupling of PZT/Ni.…”

“…13 Comparison of the measured α ME values of PZT/Ni film composites with the ideally obtainable ones suggest that there is room for improvement in ME coupling of PZT/Ni. 14 It is well known that the piezoelectric response of ceramics can be tailored by tuning their composition (via suitable stoichiometry and doping) and microstructural design (via grain and domain engineering). [16][17][18][19] Crystallographically oriented piezoelectric ceramic films have been shown to demonstrate better piezoelectric performance than their randomly oriented counterparts.…”