Skyrmion imaging and electrical detection via topological Hall (TH) effect are two primary techniques for probing magnetic skyrmions which hold promise for next-generation magnetic storage. However, these two kinds of complementary techniques have rarely been employed to investigate the same samples. We report the observation of nanoscale skyrmions in SrIrO3/SrRuO3 (SIO/SRO

Electrical detection of topological magnetic textures such as skyrmions is currently limited to conducting materials. While magnetic insulators offer key advantages for skyrmion technologies with high speed and low loss, they have not yet been explored electrically. Here, we report a prominent topological Hall effect in Pt/Tm 3 Fe 5 O 12 bilayers, where the pristine Tm 3 Fe 5 O 12 epitaxial films down to 1.25 unit cell thickness allow for tuning of topological Hall stability over a broad range from 200 to 465 K through atomic-scale thickness control. Although Tm 3 Fe 5 O 12 is insulating, we demonstrate the detection of topological magnetic textures through a novel phenomenon: "spin-Hall topological Hall effect" (SH-THE), where the interfacial spin-orbit torques allow spin-Hall-effect generated spins in Pt to experience the unique topology of the underlying skyrmions in Tm 3 Fe 5 O 12 . This novel electrical detection phenomenon paves a new path for utilizing a large family of magnetic insulators in future skyrmion technologies.

Interfacial Dzyaloshinskii-Moriya interaction (DMI) is responsible for the emergence of topological spin textures such as skyrmions in layered structures based on metallic and insulating ferromagnetic films. However, there is active debate on where the interfacial DMI resides in magnetic insulator systems. We investigate the topological Hall effect, which is an indication of spin textures, in Tm 3 Fe 5 O 12 films capped with various metals. The results reveal that Pt, W, and Au induce strong interfacial DMI and topological Hall effect, while Ta and Ti cannot. This study also provides insights into the mechanism of electrical detection of spin textures in magnetic insulator heterostructures.

We report on the magnetic and structural properties of ferromagnetic-insulating La 2 CoMnO 6 thin films grown on top of (001) STO substrates by means of RF sputtering technique. Careful structural analysis, by using synchrotron X-ray diffraction, allows identifying two different crystallographic orientations that are closely related to oxygen stoichiometry and to the features (coercive fields and remanence) of the hysteresis loops.Both Curie temperature and magnetic hysteresis turn out to be dependent on the oxygen stoichiometry. In situ annealing conditions allow tailoring the oxygen content of the films, therefore controlling their microstructure and magnetic properties. PACS: 75.70.Ak, 81.15.Cd 4 Bulk La 2 CoMnO 6 (LCMO) double perovskite has been the subject of strong interest during the last years [ 1,2,3,4,5,6,7] due to its ferromagnetic insulating character.Besides its perspectives as magnetodielectric material, LCMO is a good candidate for active insulating barriers in spin filters. For these devices, insulating barriers must be thin enough to enable tunneling conduction. The properties of epitaxial LCMO thin films have been the subject of some theoretical and experimental works in the recent years [ 8,9,10,11]. Previous experimental reports based on films prepared by pulsed laser deposition (PLD) suggest that magnetic properties are strongly dependent on growth conditions. When samples are grown under low oxygen pressure the Curie temperature (T C ) is around 100K while increasing oxygen pressure (200 mTorr and above) T C values around 230 K can be achieved. Nevertheless, there is no clear consensus on whether this variation of T C comes from differences on the Co/Mn cationic ordering [ 10] or from changes in the oxygen stoichiometry [ 9]. On the other hand, low temperature hysteresis loops reported in the literature present anomalies and "biloop" features that have been attributed to the existence of a bidomain structure in the films. However, these "biloop" features of hysteresis cycles are present up to T C =230K and therefore, cannot be linked to the persistence of regions with low T C phase [ 10].Previous studies report low temperature hysteresis loops with a saturation magnetization close to 6  B /f.u. [ 8,9,10] [ 12,13,14] are antiferromagnetic (AF). Therefore, it is expected that the existence of antisites will reduce the saturation magnetization from 6  B /f.u.. Thus, the departure of the saturation magnetization of a given sample from this saturation value can be interpreted as a measure of the degree of Co/Mn disorder in the structure.The effect of Co/Mn disorder on the magnetic properties has been previously studied in bulk samples (where it can be precisely quantified by means of neutron powder diffraction) [ 6]. These studies show that hysteresis loops become wider (with higher coercive field and lower remanence) in the presence of disorder [ 2,4,6]. Co/Mn ordering temperature is around 1125ºC and the ordering process is blocked below 1000ºC due to extremely large relaxation...

Lattice-mismatched epitaxial films of La0.7Sr0.3MnO3 (LSMO) on LaAlO3 (001) substrates develop a crossed pattern of misfit dislocations above a critical thickness of 2.5 nm. Upon film thickness increases, the dislocation density progressively increases, and the dislocation spacing distribution becomes narrower. At a film thickness of 7.0 nm, the misfit dislocation density is close to the saturation for full relaxation. The misfit dislocation arrangement produces a 2D lateral periodic structure modulation (Λ ≈ 16 nm) alternating two differentiated phases: one phase fully coherent with the substrate and a fully relaxed phase. This modulation is confined to the interface region between film and substrate. This phase separation is clearly identified by X-ray diffraction and further proven in the macroscopic resistivity measurements as a combination of two transition temperatures (with low and high Tc). Films thicker than 7.0 nm show progressive relaxation, and their macroscopic resistivity becomes similar than that of the bulk material. Therefore, this study identifies the growth conditions and thickness ranges that facilitate the formation of laterally modulated nanocomposites with functional properties notably different from those of fully coherent or fully relaxed material.

of materials properties by altering the subtle energy landscape of competing interactions through epitaxial strain and dissimilarity. [1,2] Notably, this strategy has led to the discovery of exotic interfacial phenomena, [3,4] while opening the possibility to tune the bulk transport, magnetic, ferroelectric, and multiferroic properties of thin films. [5][6][7][8][9] However, next generation nanodevices demand a further step toward miniaturization, facing challenging strategies to controllably manipulate the lateral modulation of atomic length scales. In semiconductor epitaxy, this goal can be achieved through the Stranski-Krastanov growth mode, leading to the formation of self-assembled quantum dots on a wetting layer [10] driven by lateral gradients in the surface chemical potential. [11] This strategy, however, typically leads to nanostructures exhibiting broad size distributions and poor positional order. Strained films, on the other hand, usually relax by misfit dislocations (MDs) above a critical thickness at which their elastic energy exceeds the energy of the interfacial dislocation network. [12] The overlapping of strain fields emanating from individual dislocations causes lateral modulations of lattice distortions which may extent up to the free surface. Therefore, highly organized MD networks buried at the substrate-film interface not only modulate the physical properties of thin films, but in addition can promote the growth of ordered nanostructures on their surfaces. In this sense, MDs have been used to produce strain guided patterned surfaces in semiconductor [13,14] and metal [15,16] systems, and more recently to tune Dirac surface sates in topological insulators. [17] However, to date, the extension of this concept to oxide epitaxy remains elusive.A unique property of dislocations, that make them highly appealing for creating new functional nanostructures, is their multiscale character. While being essentially linear defects, they store their elastic energy at comparatively large distances (several nanometers) from their sub-nanometer core. As a consequence, they can modify the properties of the host material in two different length scales. On the one hand, dislocation lines can be considered as a separate phase exhibiting its own physical behavior. [18] A clear manifestation of their singularity, for instance, comes from the observation that oxygen deficient dislocations in SrTiO 3 [19][20][21][22] exhibit bistable resistive switching, [23] Interfacial dissimilarity has emerged in recent years as the cornerstone of emergent interfacial phenomena, while enabling the control of electrical transport and magnetic behavior of complex oxide epitaxial films. As a step further toward the lateral miniaturization of functional nanostructures, this work uncovers the role of misfit dislocations in creating periodic surface strain patterns that can be efficiently used to control the spatial modulation of mass transport phenomena and bandwidth-dependent properties on a ≈20 nm length scale. The spontaneous forma...

Misfit dislocations form self-organized nanoscale linear defects exhibiting their own distinct structural, chemical, and physical properties which, particularly in complex oxides, hold a strong potential for the development of nanodevices. However, the transformation of such defects from passive into potentially active functional elements necessitates a deep understanding of the particular mechanisms governing their formation. Here we combine different atomic resolution imaging and spectroscopic techniques to determine the complex structure of misfit dislocations in the perovskite type La 0.67 Sr 0.33 MnO 3 /LaAlO 3 heteroepitaxial system. It is found that while the position of the film-substrate interface is blurred by cation intermixing, oxygen vacancies selectively accumulate at the tensile region of the dislocation strain field. Such accumulation of vacancies is accompanied by the reduction of manganese 2 cations in the same area, inducing chemical expansion effects which partly accommodate the dislocation strain. The formation of oxygen vacancies is only partially electrically compensated and results in a positive net charge q ~ +0.3±0.1 localized in the tensile region of the dislocation, while the compressive region remains neutral. Our results highlight a prototypical core model for perovskite based heteroepitaxial systems and offer insights for predictive manipulation of misfit dislocation properties.

In all cases the values correspond to their particular defect equilibrium and degree of charge localization. The oxygen surface exchange kinetics was also evaluated from in-situ time-resolved analyses of the cell parameter variations. LSC, LNO and GBCO films show fast oxygen reduction kinetics, k chem = 5 · 10 −6 , 3 · 10 −6 , and 2 · 10 −7 cm/s at 700 • C, respectively, in relative agreement with reported values, while BSCF films show much slower kinetics than expected, below k chem = 10 −7 cm/s at 650 • C, related to the degradation process observed in the films.