Thickness-Dependent Crossover from Charge- to Strain-Mediated Magnetoelectric Coupling in Ferromagnetic/Piezoelectric Oxide Heterostructures

Spurgeon, Steven R.; Sloppy, Jennifer D.; Kepaptsoglou, Demie; Balachandran, Prasanna V.; Nejati, Siamak; Karthik, J.; Damodaran, Anoop R.; Johnson, Craig; Ambaye, Hailemariam; Goyette, R.; Lauter, Valeria; Ramasse, Quentin M.; Idrobo, Juan Carlos; Lau, Kenneth K. S.; Lofland, S. E.; Rondinelli, James M.; Martin, Lane W.; Taheri, Mitra L.

doi:10.1021/nn405636c

Cited by 61 publications

(63 citation statements)

References 81 publications

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“…Moreover, earlier reports [30] pointed out that substrate-induced strain effects, altering the c/a ratio of the MnO 6 octahedra, drive the lowering in energy of either the 3dz 2 (i.e., compressive strain) or the 3dx 2 − y 2 (tensile strain) orbitals which, subsequently, modify the magnetic properties of the system. The latter effect has been also recently proved by Spurgeon and coworkers studying the charge-and strain-mediated effect on the magnetization and, consequently, on the P -dependent 3d orbital anisotropy occupancy of a gated LSMO (x = 0.3) layer [31]. All these arguments need to propose a valid model that can be used to qualitatively explain the observed modulation of the H a values establishing a link between the ferroelectrically induced displacements of the interfacial Mn and O ions of the LSMO and the Mn 3d orbital reconstruction (different overlapping and filling).…”

Section: Discussionmentioning

confidence: 61%

Tailoring the interfacial magnetic anisotropy in multiferroic field-effect devices

et al. 2014

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Ferroelectric field-effect devices based on perovskite oxide materials offer a new possibility to exploit emergent interfacial effects such as the electrostatic modification of the transport and magnetic properties of strongly correlated materials and to prove the magneto-electric coupling at the interface between the two different ferroic materials. Here we report on the reversible modulation of the interfacial magnetic and magnetotransport properties of La 0.825 Sr 0.175 MnO 3 thin films induced by switching the ferroelectric polarization of a top PbZr 0.2 Ti 0.8 O 3 layer. Anisotropic magnetoresistance (AMR) measurements were performed applying a magnetic field H in a plane perpendicular to the current density. By rotating H from the out-of-plane towards the in-plane direction, upon the ferroelectric polarization switching, a modulation of the normalized AMR amplitude was achieved. The dynamical electrostatic coupling at the interface of the two oxides is responsible for a reconstruction of the Mn 3de g orbitals which in turn affects the surface magnetic anisotropy of the magneto-electric system. The present work might have a broader impact, including in the field of multiferroic tunnel junctions, due to a better understanding of the coupling at the interface of the two ferroic oxides where the influence of the polarization on the magnetic degree of freedom is accomplished.

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Section: Discussionmentioning

confidence: 61%

Tailoring the interfacial magnetic anisotropy in multiferroic field-effect devices

et al. 2014

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“…Moreover, it is known that a suppression of ferroelectric polarization may occur at interfaces, but it is unclear how this may play a role in the LSMO/PZT system 17 . Recently, Lu et al 18 have proposed a theoretical mechanism whereby charge-transfer screening electrostatically dopes an interface region of the LSMO into a paramagnetic insulating state, which might explain the larger screening lengths we and others have measured 16,19 . More insight is clearly needed into local ferroelectric polarization and the presence of such a 'doping-induced double layer,' which would have fundamental implications for oxide-based electronics.…”

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confidence: 54%

“…We have used a substrate-induced self-poling technique to spontaneously pole the PZT layer during growth, as previously described 16 . We first deposited a B12 nm La 0.7 Sr 0.3 MnO 3 layer onto a bulk SrTiO 3 (001) (STO) substrate using pulsed laser deposition.…”

Section: Resultsmentioning

confidence: 99%

“…However, this effect alone was insufficient to explain the measured interface magnetization, so the authors suggested that an associated spin structure change may also occur. We have recently shown that charge-transfer screening acts in concert with local strain fluctuations to mediate coupling, and that the dominant coupling mechanism appears to depend on film geometry 16 . Moreover, it is known that a suppression of ferroelectric polarization may occur at interfaces, but it is unclear how this may play a role in the LSMO/PZT system 17 .…”

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confidence: 99%

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Polarization screening-induced magnetic phase gradients at complex oxide interfaces

et al. 2015

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Thin-film oxide heterostructures show great potential for use in spintronic memories, where electronic charge and spin are coupled to transport information. Here we use a La 0.7 Sr 0.3 MnO 3 (LSMO)/PbZr 0.2 Ti 0.8 O 3 (PZT) model system to explore how local variations in electronic and magnetic phases mediate this coupling. We present direct, local measurements of valence, ferroelectric polarization and magnetization, from which we map the phases at the LSMO/PZT interface. We combine these experimental results with electronic structure calculations to elucidate the microscopic interactions governing the interfacial response of this system. We observe a magnetic asymmetry at the LSMO/PZT interface that depends on the local PZT polarization and gives rise to gradients in local magnetic moments; this is associated with a metal-insulator transition at the interface, which results in significantly different charge-transfer screening lengths. This study establishes a framework to understand the fundamental asymmetries of magnetoelectric coupling in oxide heterostructures.

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“…There seems to be a consensus that, when interfaced with ferroelectric films, the valence of Mn in LSMO is prone to exhibit deviations from its nominal values (25,28,29,57,58), and this valence change was considered as the origin of magnetic modulation (25,28,59,60). To verify possible mechanisms, we extracted the Mn and Ti valence states from EELS (61) for all three films, and the results are summarized in Fig.…”

Section: Significancementioning

confidence: 99%

Interface-induced multiferroism by design in complex oxide superlattices

Guo

Wang

Dong

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Interfaces between materials present unique opportunities for the discovery of intriguing quantum phenomena. Here, we explore the possibility that, in the case of superlattices, if one of the layers is made ultrathin, unexpected properties can be induced between the two bracketing interfaces. We pursue this objective by combining advanced growth and characterization techniques with theoretical calculations. Using prototype La 2/3 Sr 1/3 MnO 3 (LSMO)/ BaTiO 3 (BTO) superlattices, we observe a structural evolution in the LSMO layers as a function of thickness. Atomic-resolution EM and spectroscopy reveal an unusual polar structure phase in ultrathin LSMO at a critical thickness caused by interfacing with the adjacent BTO layers, which is confirmed by first principles calculations. Most important is the fact that this polar phase is accompanied by reemergent ferromagnetism, making this system a potential candidate for ultrathin ferroelectrics with ferromagnetic ordering. Monte Carlo simulations illustrate the important role of spin-lattice coupling in LSMO. These results open up a conceptually intriguing recipe for developing functional ultrathin materials via interface-induced spin-lattice coupling.spin-lattice coupling | interfaces | magnetic/electric | structural transition | ultrathin films I nterface physics has emerged as one of the most popular methods to discover unique phenomena caused by broken symmetry (1-6). In transition metal oxide (TMO) interfaces, the different electronic, magnetic, lattice, and orbital properties of two adjoined materials lead to fascinating properties that are often radically different from those of the two component bulk materials (7-10). It would seem that we are on the verge of being able to design (11) or engineer (12) the properties of interfaces.Although the behavior of individual interfaces has been widely investigated, how two or more interfaces behave within superlattices (SLs) remains an interesting and open topic (13,14). As shown in Fig. 1A, when two interfaces are geometrically close enough, they can drastically alter the properties of the material in between because of proximity effects. Unlike layered compounds, such as Fe-based superconductors and cuprates, which have pronounced 2D properties, most perovskites with the chemical formula ABO 3 exhibit drastic decreases in their functionalities under reduced dimensionality (i.e., ultrathin materials). This property has hindered the exploration and development of active low-dimensional materials (15, 16). Therefore, exploring ultrathin materials confined by two interfaces is a rational approach to see whether interfacial effects can be exploited to achieve desired functionalities.In this work, we present an example of using the structural phase change induced by two adjacent interfaces as a route to design ultrathin TMOs. We choose two materials with distinct properties: BaTiO 3 (BTO), which in its bulk form, is polar ferroelectric, and La 2/3 Sr 1/3 MnO 3 (LSMO), which in its bulk form, is nonpolar/tilt ferromagnetic....

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Thickness-Dependent Crossover from Charge- to Strain-Mediated Magnetoelectric Coupling in Ferromagnetic/Piezoelectric Oxide Heterostructures

Cited by 61 publications

References 81 publications

Tailoring the interfacial magnetic anisotropy in multiferroic field-effect devices

Tailoring the interfacial magnetic anisotropy in multiferroic field-effect devices

Polarization screening-induced magnetic phase gradients at complex oxide interfaces

Interface-induced multiferroism by design in complex oxide superlattices

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