Ingrid Hallsteinsen

Ingrid Hallsteinsen
Norwegian University of Science and Technology | NTNU · Department of Materials Science and Engineering

MS in Nanotechnology

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27
Publications
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295
Citations

Publications

Publications (27)
Article
Antiferromagnetic (AF) thin films typically exhibit a multidomain state, and control of the AF Néel vector is challenging, as AF materials are robust to magnetic perturbations. In this paper, uniaxial Néel vector control is demonstrated by relying on anisotropic strain engineering of epitaxial thin films of the prototypical AF material LaFeO3 (LFO)...
Preprint
Antiferromagnetic thin films typically exhibit a multi-domain state, and control of the antiferromagnetic N\'eel vector is challenging as antiferromagnetic materials are robust to magnetic perturbations. By relying on anisotropic in-plane strain engineering of epitaxial thin films of the prototypical antiferromagnetic material LaFeO3, uniaxial N\'e...
Article
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The interconversion of charge and spin currents via spin-Hall effect is essential for spintronics. Energy-efficient and deterministic switching of magnetization can be achieved when spin polarizations of these spin currents are collinear with the magnetization. However, symmetry conditions generally restrict spin polarizations to be orthogonal to b...
Article
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
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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 to be effective, demands thin film materials with large Seebeck coefficients. In spintronics, the antiferromagnetic metal IrMn has been used as the pinning la...
Article
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We investigate the effect of strain and film thickness on the orbital and magnetic properties of LaSrCrO3(LSCO)/LaSrMnO3 (LSMO) heterostructures using bulk magnetometry, soft x-ray magnetic spectroscopy, first-principles density-functional theory, high-resolution electron microscopy, and x-ray diffraction. We observe an antiparallel ordering of the...
Preprint
Full-text available
The spin-Hall effect describes the interconversion of charge currents and spin currents, enabling highly efficient manipulation of magnetization for spintronics. Symmetry conditions generally restrict polarizations of these spin currents to be orthogonal to both the charge and spin flows. Spin polarizations can deviate from such direction in nonmag...
Preprint
Full-text available
We investigate the effect of strain and film thickness on the orbital and magnetic properties of LaSrCrO$_3$ (LSCO)/LaSrMnO$_3$ (LSMO) heterostructures using bulk magnetometry, soft X-ray magnetic spectroscopy, first-principles density functional theory, high-resolution electron microscopy and X-ray diffraction. We observe an anti-parallel ordering...
Article
In this study, we report on a shape-imposed magnetic anisotropy in micro- and nanostructures defined in antiferromagnetic (AF) LaFeO3 (LFO) thin films. Two distinct types of structures are investigated: embedded magnets created via ion implantation and free-standing magnets created via ion milling. Using a combination of x-ray photoemission electro...
Article
We report the effects of nitrogen diffusion on exchange bias in MnN/CoFeB heterostructures as a function of MnN thickness and field-annealing temperature. We find that competing effects occur in which high-temperature annealing enhances exchange bias in heterostructures with thick MnN through improved crystallinity, but in thinner samples this anne...
Article
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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 is demonstrated that visualizes the presence and strength of atomic movements leading to a period doubling of the unit c...
Article
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We have studied the interface magnetodynamic properties of La0.7Sr0.3MnO3/SrTiO3 (111) heterostructures by Ferromagnetic resonance spectroscopy (FMR). In addition to the bulk FMR mode, the measurements indicate a mode originating from an independently excited ferromagnetic layer at the interface. The peak-to-peak intensity of the interface mode sug...
Article
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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 a combination of x-ray photoemission electron microscopy and x-ray absorption spectroscopy, the Néel vector is shown to reorient 90° as a result o...
Article
Exchange bias occurs in field-cooled antiferromagnet/ferromagnet systems and can most often be explained in terms of uncompensated magnetic moments at the interface that are pinned in their orientation during field cooling. The presence of spin-flop coupling is often associated with spin-compensated interfaces. Here, we report exchange bias in comp...
Preprint
Full-text available
Determining the 3-dimensional crystallography of a material with sub-nanometre resolution is essential to understanding strain effects in epitaxial thin films. A new scanning transmission electron microscopy imaging technique is demonstrated that visualises the presence and strength of atomic movements leading to a period doubling of the unit cell...
Article
Full-text available
Engineering of emergent properties at oxide interfaces is an exciting route towards realizing oxide electronics. Such properties are often the result of a balance between cooperating and competing mechanisms in the materials which are difficult to decouple. In this paper, we address the interplay between an antiferromagnetic spin axis and the occur...
Article
Using strain, i.e. subtle changes in lattice constant in a thin film induced by the underlying substrate, opens up intriguing new way to control materials properties. We present a study of the effects of strain on structural and ferromagnetic properties of (111)pc-oriented La0.7Sr0.3MnO3 epitaxial thin films grown on NdGaO3, SrTiO3, and DyScO3 subs...
Article
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In antiferromagnetic spintronics control of the domains and corresponding spin axis orientation is crucial for devices. Here we investigate the antiferromagnetic axis in (111)-oriented LaFeO3/SrTiO3, which is coupled to structural twin domains. The structural domains have either the orthorhombic a- or b-axis along the in-plane ⟨11¯0⟩ cubic directio...
Article
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We observe an induced switchable magnetic moment of 1.6±0.40μB/Fe for the nominally antiferromagnetic LaFeO3 extending two to four interface layers into the non–charge transfer system La0.7Sr0.3MnO3/LaFeO3/SrTiO3(111). Simultaneously a mismatch of oxygen octahedra rotations at the interface implies an atomic reconstruction of reduced symmetry at th...
Article
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We have investigated the magnetodynamic properties of La0.7Sr0.3MnO3 (LSMO) films of thickness 10, 15 and 30 nm grown on (111)-oriented SrTiO3 (STO) substrates by pulsed laser deposition. Ferromagnetic resonance (FMR) experiments were performed in the temperature range 100–300 K, and the magnetodynamic damping parameter α was extracted as a functio...
Article
Thresholds for beam damage have been assessed for La0.7Sr0.3MnO3 and SrTiO3 as a function of electron probe current and exposure time at 80 and 200kV acceleration voltage. The materials were exposed to an intense electron probe by aberration corrected scanning transmission electron microscopy (STEM) with simultaneous acquisition of electron energy...
Article
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div class="title">Towards Mapping Perovskite Oxide 3-D Structure Using Two-Dimensional Pixelated STEM Detector - Volume 22 Issue S3 - Magnus Nord, Andrew Ross, Ingrid Hallsteinsen, Thomas Tybell, Ian MacLaren
Article
In crystalline thin film growth a prerequisite is substrate surfaces with a stable and uniform structure and chemical composition. Various substrate treatments were used to obtain atomically smooth, step-and-terrace (111)-oriented SrTiO3 with uniform cation layers at the surface, i.e., single termination. The surface control enables subsequent laye...
Conference Paper
Full-text available
We report on structural domains in LaFeO3 epitaxial thin films on (111) oriented SrTiO3 observed by transmission electron microscopy using low magnification dark field imaging and high resolution transmission electron microscopy techniques. The films were grown by pulsed laser deposition and had a thickness ≈ 20 nm. Three domain orientations are fo...
Poster
Full-text available
Epitaxial thin films (approximately 20 nm) of the perovskite LaFeO3 (LFO) on (111) oriented SrTiO3 (STO) has been studied by transmission electron microscopy (TEM). The LFO thin film forms structural domains on the substrate, according to its orthorhombic structure. Inside the domains there are lines of reduced bragg scattering, which hints at a co...
Article
Full-text available
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, magnetic properties of (111)-oriented La0.7Sr0.3MnO3 thin films are elucidated by correlating macroscopic and local properties. The...
Article
Full-text available
We report on the stability of the La0.7Sr0.3MnO3 thin film surface when deposited on (111)-oriented SrTiO3. For ultrathin La0.7Sr0.3MnO3 films, an initial 3-dimensional morphology is observed, which becomes 2-dimensional with increasing film thickness. For even thicker samples, we show that the surface morphology evolves from 2-dimensional to 3-dim...

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Projects (2)
Archived project
To study the crystallography, quality, and the interface region of the LFO thin film when grown on (111) oriented STO. LFO is antiferromagnetic in bulk and is an interesting model material when investigating e.g. the giant magneto resistance effect.