Strain-Mediated Converse Magnetoelectric Coupling in La_0.7Sr_0.3MnO₃/Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ Multiferroic Heterostructures

Abstract

The converse magnetoelectric (ME) coupling of a La0.7Sr0.3MnO3 (LSMO) thin film, deposited on piezoelectric Pb­(Mg1/3Nb2/3)­O3–PbTiO3 (PMN–PT) single crystal substrate by the pulsed laser deposition (PLD) technique, was investigated by magneto-optical Kerr effect (MOKE) system. Because of the piezoelectric nature of the PMN–PT, the strain status of the LSMO thin film is tunable by the electric field applied on the substrate, as it is well-known that the Manganite thin film has very strong electron–phonon interaction; thus, the magnetic property change as a function of external electric field can be realized. The change of the Kerr signal of LSMO film upon applying direct current (DC) voltage to the PMN–PT single crystal was recorded. In particular, the voltage-induced change of the Kerr signal in the LSMO by applying the alternative current (AC) actuation voltage bias to the PMN–PT single crystal can be in situ recorded without external magnetic fields. The gained Kerr signal versus voltage loop basically tracks the electromechanical strain curve of the PMN–PT single crystal, distinctly certifying that a converse ME coupling in Manganite/piezoelectric heterostructures is mediated by strain rather than the interfacial effect.

Large magnetoelectric coupling in multiferroic oxide heterostructures assembled via epitaxial lift-off

“…1d), which is roughly six times larger than the roomtemperature saturation magnetization of highly strained LSMO grown directly on PMN-PT (ref. 23 ). Similarly, the release of epitaxial strain led to an increase of Curie temperature (Supplementary Note 6), as expected 48 .…”

“…Our macroscopic magnetic measurements yield two key results. First, growth using a well-matched substrate, followed by strain release via epitaxial lift-off 28,29 , resulted in an LSMO film magnetization that is greatly enhanced with respect to the value for an LSMO film that contained strain and dislocations following direct growth on PMN-PT 23 . Second, our strain-mediated magnetoelectric coupling is just as effective as strain-mediated coupling across an epitaxial interface 17,18 in spite of the incoherent bonding between our magnetostrictive film and electroactive substrate.…”

“…Unfortunately, the key properties of transition metal perovskite oxides are degraded following epitaxial growth on ferroelectric substrates, as seen for ferromagnetic films with reduced Curie temperatures and suppressed magnetizations 17,18,23 . This degradation is a consequence of the >3% lattice-parameter mismatch that causes films to experience both strain and dislocations 17,18,[24][25][26] , even if epitaxial buffer layers are present 27 .…”

“…Ferroelectric domain switching in our PMN-PT substrate is accompanied by a rhombohedral-orthorhombic phase transition, and the large resulting strain is effectively transmitted to the transferred LSMO film, whose magnetization is enhanced after epitaxial lift-off to a value that greatly exceeds the value for LSMO grown directly on PMN-PT 23 . Despite a layer of adsorbates at the interface, the magnetoelectric coupling coefficient is similar to values recorded for epitaxial heterostructures 17,18 , and a twofold magnetic anisotropy in the film can be electrically switched by 90°in a repeatable and non-volatile manner.…”

Localized strain profile in surface electrode array for programmable composite multiferroic devices

“…A tensile strain is induced along [01-1], and a compressive strain is generated along [100]. (001)-cut PMN-PT is another popular substrate choice, especially when the magnetic films require epitaxial growth, such as La0.7Sr0.3MnO3 (LSMO) 24,25 or Fe(1-x)Gax alloys 26 , with a lattice match to PMN-PT 27 . With an applied electric field, the substrate typically undergoes isotropic, in-plane compressive strain 28,29 .…”