A5031554952- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Advanced Condensed Matter Physics
- Multiferroics and related materials
- Magnetic properties of thin films
- ZnO doping and properties
- Ferroelectric and Piezoelectric Materials
- Semiconductor materials and devices
- Characterization and Applications of Magnetic Nanoparticles
- Perovskite Materials and Applications
- Magnetic Properties of Alloys
- Solid-state spectroscopy and crystallography
- Nonlinear Optical Materials Research
- Advanced X-ray Imaging Techniques
- Machine Learning in Materials Science
- Advanced Electron Microscopy Techniques and Applications
- Magneto-Optical Properties and Applications
- Modular Robots and Swarm Intelligence
- High-pressure geophysics and materials
- Nanowire Synthesis and Applications
- Copper Interconnects and Reliability
- Catalysis and Oxidation Reactions
- Induction Heating and Inverter Technology
- Hydrogen embrittlement and corrosion behaviors in metals
- Polymer crystallization and properties
Norwegian University of Science and Technology
2015-2025
Lawrence Berkeley National Laboratory
2016-2021
Oak Ridge National Laboratory
2019
University of California, Davis
2017
The interconversion of charge and spin currents via spin-Hall effect is essential for spintronics. Energy-efficient deterministic switching magnetization can be achieved when polarizations these are collinear with the magnetization. However, symmetry conditions generally restrict to orthogonal both flows. Spin deviate from such direction in nonmagnetic materials only crystalline reduced. Here, we show control polarization by using a non-collinear antiferromagnet Mn3GaN, which triangular...
In crystalline thin film growth a prerequisite is substrate surfaces with stable and uniform structure chemical composition. Various treatments were used to obtain atomically smooth, step-and-terrace (111)-oriented SrTiO3 cation layers at the surface, i.e., single termination. The surface control enables subsequent layer-by-layer epitaxial of perovskite films La0.7Sr0.3MnO3, LaFeO3, BaTiO3. Reflection high-energy electron diffraction energy loss spectroscopy revealed that chemically...
We report on the stability of La0.7Sr0.3MnO3 thin film surface when deposited (111)-oriented SrTiO3. For ultrathin films, an initial 3-dimensional morphology is observed, which becomes 2-dimensional with increasing thickness. even thicker samples, we show that evolves from to and this observation consistent Asaro-Tiller-Grinfeld instability, can be controlled by deposition temperature. This allows for synthesis films step-and-terrace surfaces over a wide range thicknesses. Structural...
We observe an induced switchable magnetic moment of $1.6\ifmmode\pm\else\textpm\fi{}0.40\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{\mathrm{B}}/\mathrm{Fe}$ for the nominally antiferromagnetic $\mathrm{LaFe}{\mathrm{O}}_{3}$ extending two to four interface layers into non--charge transfer system $\mathrm{L}{\mathrm{a}}_{0.7}\mathrm{S}{\mathrm{r}}_{0.3}\mathrm{Mn}{\mathrm{O}}_{3}\text{/}\mathrm{LaFe}{\mathrm{O}}_{3}\text{/}\mathrm{SrTi}{\mathrm{O}}_{3}(111)$. Simultaneously a mismatch...
Abstract The Seebeck effect converts thermal gradients into electricity. As an approach to power technologies in the current Internet-of-Things era, on-chip energy harvesting is highly attractive, and be effective, demands thin film materials with large coefficients. In spintronics, antiferromagnetic metal IrMn has been used as pinning layer magnetic tunnel junctions that form building blocks for random access memories sensors. Spin pumping experiments revealed Néel temperature...
We investigate the effect of strain and film thickness on orbital magnetic properties LaSrCrO$_3$ (LSCO)/LaSrMnO$_3$ (LSMO) heterostructures using bulk magnetometry, soft X-ray spectroscopy, first-principles density functional theory, high-resolution electron microscopy diffraction. observe an anti-parallel ordering moments between ferromagnetic LSMO layers LSCO spacers leading to a strain-independent ground state LSCO/LSMO for as thin 2 unit cells. As is increased, net maintained, however,...
Determining the three-dimensional (3D) crystallography of a material with subnanometer resolution is essential to understanding strain effects in epitaxial thin films. A scanning transmission electron microscopy imaging technique demonstrated that visualizes presence and strength atomic movements leading period doubling unit cell along beam direction, using intensity an extra Laue zone ring back focal plane recorded pixelated detector method. This method used together conventional...
Mixed-valence manganite thin films are attractive for spintronic devices. Crystalline orientation is a promising route to tailor switching mechanisms, as magnetization reversal depends on the magnetic anisotropy. Here, properties of (111)-oriented La0.7Sr0.3MnO3 elucidated by correlating macroscopic and local properties. The coercive field an order magnitude lower than (001)-oriented La0.7Sr0.3MnO3. Locally, 6-fold anisotropy observed, while macroscopically, isotropic response prevailing....
In thermosetting epoxies, thermomechanical properties can be enhanced by conscious selection of curing agents. Full cross-linking leads to a maximum in the glass- transition temperature. However, relation between glass temperature and epoxy matrix depends on several factors beyond degree, such as molecular weight polymers, network organization, amount branching, presence hydrogen bonds. this study, we investigated adding non- stoichiometric ratios resin Epikote 828 agent Jeffamine D230. The...
We report on structural domains in LaFeO3 epitaxial thin films (111) oriented SrTiO3 observed by transmission electron microscopy using low magnification dark field imaging and high resolution techniques. The were grown pulsed laser deposition had a thickness ≈ 20 nm. Three domain orientations are found, accordance with the orthorhombic structure of LaFeO3. themselves irregular shapes, vary size from tens to thousands nm2. Regions reduced Bragg scattering as straight lines along < 100 >,...
Using strain, i.e. subtle changes in lattice constant a thin film induced by the underlying substrate, opens up intriguing new ways to control material properties. We present study of effects strain on structural and ferromagnetic properties (1 1 1)pc-oriented La0.7Sr0.3MnO3 epitaxial films grown NdGaO3, SrTiO3, DyScO3 substrates. (The subscript pc denotes pseudo-cubic symmetry.) The results show that assumes monoclinic unit cell NdGaO3 rhombohedral SrTiO3. For uniaxial magnetic anisotropy...
In antiferromagnetic spintronics control of the domains and corresponding spin axis orientation is crucial for devices. Here we investigate in (111)-oriented LaFeO3/SrTiO3, which coupled to structural twin domains. The have either orthorhombic a- or b-axis along in-plane ⟨11¯0⟩ cubic directions substrate, magnetic sample plane. Six degenerate axes are found ⟨112¯⟩ directions. This contrast biaxial anisotropy (001)-oriented films reflects how crystal can be used antiferromagnets.
Engineering of emergent properties at oxide interfaces is an exciting route towards realizing electronics. Such are often the result a balance between cooperating and competing mechanisms in materials which difficult to decouple. In this paper, we address interplay antiferromagnetic spin axis occurrence magnetic reconstructions (111)-oriented $\mathrm{L}{\mathrm{a}}_{0.7}\mathrm{S}{\mathrm{r}}_{0.3}\mathrm{Mn}{\mathrm{O}}_{3}/\mathrm{LaFe}{\mathrm{O}}_{3}$ interface. We report critical...
We report the effects of nitrogen diffusion on exchange bias in MnN/CoFeB heterostructures as a function MnN thickness and field-annealing temperature. find that competing occur which high-temperature annealing enhances with thick through improved crystallinity, but thinner samples this ultimately eliminates due to deficiency. Using polarized neutron reflectometry magnetic x-ray spectroscopy, we directly observe increasing amounts migration from into underlying Ta seed layer increased In...
In this study, we report on a shape-imposed magnetic anisotropy in micro- and nanostructures defined antiferromagnetic (AF) LaFeO3 (LFO) thin films. Two distinct types of structures are investigated: embedded magnets created via ion implantation free-standing milling. Using combination x-ray photoemission electron microscopy absorption spectroscopy, examine the impact structure type, AF layer thickness, crystal geometry Néel vector orientation these structures. We demonstrate alike show that...
Exchange bias occurs in field-cooled antiferromagnet/ferromagnet systems and can most often be explained terms of uncompensated magnetic moments at the interface that are pinned their orientation during field cooling. The presence spin-flop coupling is associated with spin-compensated interfaces. Here, we report exchange complex oxide heterostructures antiferromagnetic ${\mathrm{LaFeO}}_{3}$ thin layers ferromagnetic...
In this study, we report on a temperature-driven antiferromagnetic (AF) spin reorientation transition in micro- and nanostructures of AF/ferromagnetic (FM) LaFeO3/La0.7Sr0.3MnO3 thin film bilayers. Using combination x-ray photoemission electron microscopy absorption spectroscopy, the Néel vector is shown to reorient 90° as result competition between shape-imposed anisotropy AF layer interface coupling adjacent FM layer. We demonstrate how temperature dependence AF/FM configuration...
Antiferromagnetic thin films typically exhibit a multi-domain state, and control of the antiferromagnetic N\'eel vector is challenging as materials are robust to magnetic perturbations. By relying on anisotropic in-plane strain engineering epitaxial prototypical material LaFeO3, uniaxial demonstrated. Orthorhombic (011)- (101)-oriented DyScO3, GdScO3 NdGaO3 substrates used engineer different states. The stabilises structurally monodomain monoclinic LaFeO3 films. found along tensile strained...
We have studied the interface magnetodynamic properties of La0.7Sr0.3MnO3/SrTiO3 (111) heterostructures by Ferromagnetic resonance spectroscopy (FMR). In addition to bulk FMR mode, measurements indicate a mode originating from an independently excited ferromagnetic layer at interface. The peak-to-peak intensity suggests thickness on order few unit cells. Angle resolved reveal hexagonal symmetry magnetocrystalline anisotropy with easy axis along in-plane &lt;1–10&gt; crystallographic...
Journal Article Towards Mapping Perovskite Oxide 3-D Structure Using Two-Dimensional Pixelated STEM Detector Get access Magnus Nord, Nord School of Physics and Astronomy, University Glasgow, United Kingdom Search for other works by this author on: Oxford Academic Google Scholar Andrew Ross, Ross Ingrid Hallsteinsen, Hallsteinsen Department Electronics Telecommunication, Norwegian Science Technology, Trondheim, Norway Thomas Tybell, Tybell Ian MacLaren Microscopy Microanalysis, Volume 22,...