Interfacial tuning of chiral magnetic interactions for large topological Hall effects in LaMnO/SrIrO heterostructures.

Chiral interactions in magnetic systems can give rise to rich physics manifested, for example, as nontrivial spin textures. The foremost interaction responsible for chiral magnetism is the Dzyaloshinskii-Moriya interaction (DMI), resulting from inversion symmetry breaking in the presence of strong spin-orbit coupling. However, the atomistic origin of DMIs and their relationship to emergent electrodynamic phenomena, such as topological Hall effect (THE), remain unclear.

Magnetic-Field Control of Topological Electronic Response near Room Temperature in Correlated Kagome Magnets.

Strongly correlated kagome magnets are promising candidates for achieving controllable topological devices owing to the rich interplay between inherent Dirac fermions and correlation-driven magnetism. Here we report tunable local magnetism and its intriguing control of topological electronic response near room temperature in the kagome magnet Fe_{3}Sn_{2} using small angle neutron scattering, muon spin rotation, and magnetoresistivity measurement techniques. The average bulk spin direction and magnetic domain texture can be tuned effectively by small magnetic fields.

Nanoscale magnetization inhomogeneity within single phase nanopillars.

We report observation of a radial dependence in the magnetic anisotropy of epitaxially strained CoFeO nanopillars in a BaTiO matrix. This archetypal example of a multiferroic heterostructure with a self-assembling three-dimensional architecture possesses significant out-of-plane uniaxial magnetic anisotropy. The anisotropy originates from the large magnetostriction of CoFeO and the state of stress within the nanocomposite.

Exploiting Symmetry Mismatch to Control Magnetism in a Ferroelastic Heterostructure.

In the bulk, LaCoO_{3} (LCO) is a paramagnet, yet the low-temperature ferromagnetism (FM) is observed in tensile strained thin films, and its origin remains unresolved. Here, we quantitatively measured the distribution of atomic density and magnetization in LCO films by polarized neutron reflectometry (PNR) and found that the LCO layers near the heterointerfaces exhibit a reduced magnetization but an enhanced atomic density, whereas the film's interior (i.e.

Nanoscale ferroelastic twins formed in strained LaCoO films.

The coexistence and coupling of ferroelasticity and magnetic ordering in a single material offers a great opportunity to realize novel devices with multiple tuning knobs. Complex oxides are a particularly promising class of materials to find multiferroic interactions due to their rich phase diagrams, and are sensitive to external perturbations. Still, there are very few examples of these systems.

Large orbital polarization in nickelate-cuprate heterostructures by dimensional control of oxygen coordination.

Artificial heterostructures composed of dissimilar transition metal oxides provide unprecedented opportunities to create remarkable physical phenomena. Here, we report a means to deliberately control the orbital polarization in LaNiO (LNO) through interfacing with SrCuO (SCO), which has an infinite-layer structure for CuO. Dimensional control of SCO results in a planar-type (P-SCO) to chain-type (C-SCO) structure transition depending on the SCO thickness.

Oxygen Diode Formed in Nickelate Heterostructures by Chemical Potential Mismatch.

Deliberate control of oxygen vacancy formation and migration in perovskite oxide thin films is important for developing novel electronic and iontronic devices. Here, it is found that the concentration of oxygen vacancies (V ) formed in LaNiO (LNO) during pulsed laser deposition is strongly affected by the chemical potential mismatch between the LNO film and its proximal layers. Increasing the V concentration in LNO significantly modifies the degree of orbital polarization and drives the metal-insulator transition.

Spatially Resolved Large Magnetization in Ultrathin BiFeO.

Here, a quantitative magnetic depth profile across the planar interfaces in BiFeO /La Sr MnO (BFO/LSMO) superlattices using polarized neutron reflectometry is obtained. An enhanced magnetization of 1.83 ± 0.

Orientation Control of Interfacial Magnetism at LaSrMnO/SrTiO Interfaces.

Understanding the magnetism at the interface between a ferromagnet and an insulator is essential because the commonly posited magnetic "dead" layer close to an interface can be problematic in magnetic tunnel junctions. Previously, degradation of the magnetic interface was attributed to charge discontinuity across the interface. Here, the interfacial magnetism was investigated using three identically prepared LaSrMnO (LSMO) thin films grown on different oriented SrTiO (STO) substrates by polarized neutron reflectometry.

Influence of vanadium-doping on the magnetism of FeCo/SiO2 nanoparticle.

FeCo nanoparticles (4 ± 1 nm), encapsulated by SiO2, were synthesized with and without a 2% (atomic ratio) vanadium doping. The impact from the presence of vanadium, an additive often used in the bulk to alter both physical and mechanical properties, on the nanomagnetism was probed by element-specific X-ray spectroscopy and magnetometry techniques. While the nanostructure was unaffected by the addition of 2% vanadium, the temperature dependent magnetic properties were altered significantly, such as the increased coercivity and an exchange bias field shift.

Spontaneously formed interfacial metal silicates and their effect on the magnetism of superparamagnetic FeCo/SiO₂ core/shell nanoparticles.

The integration of superparamagnetic core/shell nanoparticles into devices and other nanoscale technological applications requires a detailed understanding of how the intimate contact between core and shell nanophases affects the magnetism. We report how, for single-domain FeCo nanoparticles, an FeCo phase unique to the nanoscale with silica shells of increasing thicknesses spontaneously formed interfacial metal silicates between the core and shell (such as Fe2SiO4 and Co2SiO4) and altered the overall magnetism of the nanomaterial significantly. The influence of this previously overlooked phenomenon on magnetic properties is reported.

Hierarchical self-assembly and optical disassembly for controlled switching of magnetoferritin nanoparticle magnetism.

Protein cages such as ferritin and viral capsids are interesting building blocks for nanotechnology due to their monodisperse structure and ability to encapsulate various functional moieties. Here we show that recombinant ferritin protein cages encapsulating Fe(3)O(4)-γ-Fe(2)O(3) iron oxide (magnetoferritin) nanoparticles and photodegradable Newkome-type dendrons self-assemble into micrometer-sized complexes with a face-centered-cubic (fcc) superstructure and a lattice constant of 13.1 nm.