Significant Strain‐Induced Orbital Reconstruction and Strong Interfacial Magnetism in TiNi(Nb)/Ferromagnet/Oxide Heterostructures via Oxygen Manipulation

Abstract

Dynamical manipulation of oxygen ion (O 2− ) at metal/oxide heterointerfaces is widely demonstrated to tailor numerous physical and chemical properties and facilitate creating novel functionalities significantly. The traditional works mainly focus on electric control of O 2− dynamical behavior and related interface characteristics. Here, an alternative strategy is reported to modulate O 2− transport and interfacial magnetism via a significant strain induced by shape memory effect, which is different from the conventional magnetoelastic coupling mechanism. By driving the martensite to austenite transition in TiNi(Nb) shape memory alloy substrates, a significant and tunable strain is exerted on Pt/Co/MgO heterostructure, which promotes interfacial O 2− migration in a nonvolatile manner. The O 2− migration induces an orbital reconstruction of Co to tune the orbital magnetism noticeably, which strengthens the interfacial magnetic anisotropy energy by two times to a striking value of 0.95 erg cm −2 . Besides, the overall magnetic anisotropy is broadly tunable from in-plane to perpendicular direction by an elaborate strain engineering with changing Co thickness. This work develops a nonelectrical oxygen manipulation for tailoring ion-controlled interfacial properties universally and also clarifies the magnetoionic coupling origin for enriching the oxygen-related orbital physics and functional device applications. and interfacial performance can advance the metal/oxide bilayer applications to functional devices. Of particular recent interest in the information storage and sensing fields are the ferromagnetic metal (FM)/metal-oxide (MO) bilayers with a strong perpendicular magnetic anisotropy (PMA), such as CoFeB/MgO and Co/AlO x , which are the core elements of low energyconsumption spintronic devices, such as magnetic tunneling junction, magnetic random access memories, and racetrack memorizers. [19][20][21][22][23] The PMA of FM/MO bilayers mainly derives from the interfacial FM 3d-O 2p orbital hybridization that is sensitive to the interfacial oxygen environment. [1][2][3][4][5][6] Therefore, extensive works were carried out to tailor the interfacial magnetism by controlling O 2− transport especially using an electric field. [5,7,[24][25][26][27][28] The electric field can drive O 2migration to change oxidation state of FM layer, which can regulate the magnetic anisotropy energy (MAE), [7,[24][25][26][27] which paves a feasible way for markedly reducing the switching energy in solid-state spintronic devices. However, to apply an effective electric field, a thick MO layer of tens of nanometers is required to ensure its good insulativity, which may restrict the application on devices with thin MO layers. Moreover, besides the dynamical O 2− migration, the electric field also causes a static charge accumulation to affect the MAE of FM layer concurrently, [29][30][31][32][33] which makes the in-depth magnetoionic coupling origin still ambiguous. Thus, developing a Interfacial Magnetic Anisotropy

Electronic Inhomogeneity Influence on the Anomalous Hall Resistivity Loops of SrRuO3 Epitaxially Interfaced with 5d Perovskites

“…In addition, oxygen ions might migrate across the interfaces, as it has been observed in ferromagnet/oxide heterostructures. , This would induce oxygen vacancies in one layer and oxygen excess in the neighboring layer, which can influence the electronic properties of the SrRuO 3 -based heterostructures . However, the oxygen surface exchange and the oxygen diffusion coefficients were found to be comparably small in SrRuO 3 , and here, we did not address the details of the stoichiometry of the layers by any techniques.…”

Field‐Free Manipulation of Skyrmion Creation and Annihilation by Tunable Strain Engineering

“…[24,25] Moreover, Young's moduli of common metallic SMA are comparable with that of the magnetic films, facilitating effective strain transfer in tuning the electronic structure of the film significantly. [26,27] In this study, we successfully realized strainmanipulated creation and annihilation of skyrmions in [Pt/Co/ Ta] n multilayers by temperature control of the phase transition in a TiNiNb-SMA substrate. The strain effectively promoted the creation of skyrmion by lowering the nucleation field from 400 Oe to zero.…”

Giant Strain Control of Antiferromagnetic Moment in Metallic FeMn by Tuning Exchange Spring Structure

“…Shape memory alloy (SMA) is a special strain output material which can produce a significant and tunable strain (6–8%) through controlling a transformation between the martensitic and austenitic phases 36,37. The strain showed a powerful ability to modify the electronic structure and magnetic properties of FM films 38–40. In this work, a typical exchange biased Ta/NiFe/FeMn system was deposited on a TiNi(Nb)‐SMA substrate.…”