A5019471167- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Magnetic properties of thin films
- Characterization and Applications of Magnetic Nanoparticles
- Theoretical and Computational Physics
- Micro and Nano Robotics
- Advanced Condensed Matter Physics
- Metallic Glasses and Amorphous Alloys
- Physics of Superconductivity and Magnetism
- Multiferroics and related materials
- Microfluidic and Bio-sensing Technologies
- Magnetic and transport properties of perovskites and related materials
- Advanced Materials and Mechanics
- Magnetic Properties and Applications
- Advanced Electron Microscopy Techniques and Applications
- Advanced X-ray Imaging Techniques
- Pickering emulsions and particle stabilization
- Magnetism in coordination complexes
- Iron oxide chemistry and applications
- Magneto-Optical Properties and Applications
- ZnO doping and properties
- Thin-Film Transistor Technologies
- Advanced Sensor and Energy Harvesting Materials
- X-ray Spectroscopy and Fluorescence Analysis
- Electrohydrodynamics and Fluid Dynamics
University of Nebraska–Lincoln
2020-2025
Lawrence Berkeley National Laboratory
2016-2022
University of California, Santa Cruz
2018-2022
University of Cambridge
2020
University of Glasgow
2020
University of California, Berkeley
2018
Berkeley College
2017
Leibniz Institute for Solid State and Materials Research
2012-2016
Helmholtz-Zentrum Berlin für Materialien und Energie
2015
Chemnitz University of Technology
2012-2013
We fabricated self-powered colloidal Janus motors combining catalytic and magnetic cap structures, demonstrated their performance for manipulation (uploading, transportation, delivery) sorting of microobjects on microfluidic chips. The specific properties the are provided by ultrathin multilayer films that designed to align moment along main symmetry axis cap. This unique property allows a deterministic motion particles at large scale when guided in an external field. observed directional...
Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or launch novel functionalities by tailoring geometry of an object, e.g. its local curvature. In generic electronic system, curvature results appearance scalar vector geometric potentials inducing anisotropic chiral effects. specific case magnetism, even...
Liquid reconfigurable ferromagnetic materials Ferromagnetic show a permanent magnetic dipole, whereas superparamagnetic ones only properties under an applied field. Some materials, like ferrofluids, liquid-like behavior but do not retain their magnetization in the absence of Liu et al. remnant otherwise magnetite nanoparticles at oil-water interface emulsion droplets (see Perspective by Dreyfus). The could be controlled coupling and uncoupling individual nanoparticles, making it possible to...
We present fuel-free locomotion of magnetic spherical Janus motors driven by magnetically induced thermophoresis--a self-diffusive propulsion an object in any liquid media due to a local temperature gradient. Within this approach ac field is applied induce thermophoretic motion the objects via heating cap particles, while additional dc used orient and guide their on long time scale. Full control over achieved specific properties ultrathin 100-nm-thick Permalloy (Py, Fe₁₉Ni₈₁ alloys) films...
Abstract X-ray tomography is a well-established technique to characterize 3D structures in material sciences and biology; its magnetic analogue—magnetic tomography—is yet be developed. Here we demonstrate the visualization reconstruction of domain curved thin films with tubular shape by means full-field soft microscopies. The arrangement magnetization retrieved from set 2D projections analysing evolution contrast varying projection angle. Using algorithms analyse angular provides...
The scientific and technological exploration of three-dimensional magnetic nanostructures is an emerging research field that opens the path to exciting novel physical phenomena, originating from increased complexity in spin textures, topology, frustration three dimensions. One can also anticipate a tremendous potential for applications with those systems sensor information processing technologies terms improved energy efficiency, speed, functionalities, miniaturization future spintronic...
The magnetic microstructure of rolled-up nanomembranes is revealed both theoretically and experimentally. Two types are considered, one with a non-magnetic spacer layer the other without. Experimentally, by using different materials tuning dimensions nanomembranes, domain patterns consisting spiral-like azimuthally magnetized domains observed, which in qualitative agreement theoretical predictions. Inorganic stretchable,1 shapeable,2 transferrable to virtually any substrate.3, 4 These...
The first printable magnetic sensor relying on the giant magnetoresistance effect (GMR) is demonstrated. It prepared in form of magneto-sensitive inks adherent to any kind arbitrarily shaped surface. fabricated exhibits a room-temperature GMR up 8% showing great potential for contactless switching hybrid electronic circuits (discrete semiconductor and elements) applied surface by regular painting.
The magnetization distributions in individual soft magnetic permalloy caps on non-magnetic spherical particles with sizes ranging from 50 to 800 nm are investigated. We experimentally visualize the structures at resolution limit of x-ray circular dichroism photoelectron emission microscopy (XMCD-PEEM). By analyzing so-called tail contrast XMCD-PEEM, spatial is significantly enhanced, which allowed us explore vortices and their displacement curved surfaces. Furthermore, cap nanostructures...
We report an x-ray photon correlation spectroscopy method that exploits the recent development of two-pulse mode at Linac Coherent Light Source. By using coherent resonant magnetic scattering, we studied spontaneous fluctuations on nanosecond time scales in thin films multilayered Fe/Gd exhibit ordered stripe and Skyrmion lattice phases. The was found to differ between phase near stripe-Skyrmion boundary. This technique will enable a significant new area research study equilibrium condensed matter.
Curvature impacts physical properties across multiple length scales, ranging from the macroscopic scale, where shape and size vary drastically with curvature, to nanoscale at interfaces inhomogeneities in materials structural, chemical, electronic, magnetic short-range order. In quantum materials, correlations, entanglement, topology dominate, curvature opens path novel characteristics phenomena that have recently emerged could a dramatic impact on future fundamental applied studies of...
Abstract An active droplet system, programmed to repeatedly move autonomously at a specific velocity in well‐defined direction, is demonstrated. Coulombic energy stored oversaturated interfacial assemblies of charged nanoparticle‐surfactants by an applied DC electric field and can be released on demand. Spontaneous emulsification suppressed increase the stiffness assemblies. Rapidly removing releases explosive event that propels droplet, where thousands microdroplets are ballistically...
The interplay of topological defects with curvature is studied for out-of-surface magnetic vortices in thin spherical nanoshells. In the case an easy-surface Heisenberg magnet it shown that underlying surface leads to a coupling between localized component vortex its delocalized in-surface structure, i.e., polarity-chirality coupling.
We investigate the change of magnetic vortex states driven by curvature. The equilibrium state and magnetization reversal soft permalloy (Py, Ni${}_{80}$Fe${}_{20}$) caps on self-assembled spherical particles with diameters 100, 330, 800 nm are investigated, revealing ground for individual closely packed cap arrays. coupling between vortices is substantially reduced due to shape as apparent in a much weaker dependence process separation distance. Interestingly, remaining still sufficiently...
Inversion symmetry breaking has become a vital research area in modern magnetism with phenomena including the Rashba effect, spin Hall and Dzyaloshinskii-Moriya interaction (DMI)-a vector exchange. The latter one may stabilize chiral textures topologically nontrivial properties, such as Skyrmions. So far, have mainly been studied helimagnets thin ferromagnets heavy-element capping. Here, concept of chirality driven by interfacial DMI is generalized to complex multicomponent systems...
Modifying the curvature in magnetic nanostructures is a novel and elegant way toward tailoring physical phenomena at nanoscale, allowing one to overcome limitations apparent planar counterparts. Here, we address curvature-driven changes of static properties cylindrically curved segments with different radii curvature. The architectures are prepared by capping nonmagnetic micrometer- nanometer-sized rolled-up membranes soft-magnetic 20 nm thick permalloy (Ni(80)Fe(20)) film. A quantitative...
Multiferroic nanomaterials bear the potential for assembling a manifold of novel and smart devices. For room temperature (RT) applications, however, only BiFeO${}_{3}$ single-phase perovskites are candidates to date. Nevertheless, vertical heterostructures separating magnetic ferroelectric functionality into different layers now widely proposed circumvent this lack in materials' availability. We show here that second approach is very profitable as illustrated by strain-mediated coupling...
Abstract Topological magnetic states, such as chiral skyrmions, are of great scientific interest and show huge potential for novel spintronics applications, provided their topological charges can be fully controlled. So far skyrmionic textures have been observed in noncentrosymmetric crystalline materials with low symmetry at temperatures. We propose theoretically demonstrate experimentally the design spin charge densities that tailored ambient Tuning interlayer coupling vertically stacked...
Increasing performance and enabling novel functionalities of microelectronic devices, such as three-dimensional (3D) on-chip architectures in optics, electronics, magnetics, calls for new approaches both fabrication characterization. Up to now, 3D magnetic had mainly been studied by integral means without providing insight into local microstructures that determine the device performance. We prove a concept allows imaging domain patterns buried objects, example, tubular with multiple...
We use nano disk arrays with square and honeycomb symmetry to investigate magnetic phases spin correlations of XY dipolar systems at the micro scale. Utilizing magnetization sensitive X-ray photoemission electron microscopy, we probe ground states "order-by-disorder" phenomenon predicted 30 years ago. observe antiferromagnetic striped state in lattices, 6-fold symmetric structures, including trigonal vortex lattices disordered floating vortices, lattice. The frustration lattice causes a...
Tailoring structural, chemical, and electronic (dis-)order in heterogeneous media is one of the transformative opportunities to enable new functionalities sciences energy quantum materials. This endeavor requires elemental, magnetic sensitivities at nano/atomic scale two- three-dimensional space. Soft X-ray radiation hard provided by synchrotron facilities have emerged as standard characterization probes owing their inherent element-specificity high intensity. One most promising methods view...
Significance Structured functional liquids combine mechanical versatility of fluids with solid-state properties, such as ferromagnetism, and offer a route to synthesize control magnetic for adaptive liquid robotics. Studies on these intriguing materials are only in their nascent state, profound understanding the physical state is still lacking. We use hydrodynamics experiments probe how magnetization ferromagnetic droplets, governed by assembly jamming nanoparticles at liquid–liquid...
Abstract Spontaneous emulsification, resulting from the assembly and accumulation of surfactants at liquid–liquid interfaces, is an interfacial instability where microdroplets are generated diffusively spread interface until complete emulsification. Here, it shown that external magnetic field can modulate paramagnetic nanoparticle (NPSs) interfaces to trigger oversaturation in areal density NPSs interface, as evidenced by a marked reduction tension, γ, corroborated with magnetostatic...