A5016149978- Magnetic properties of thin films
- Magnetic Properties and Applications
- Advanced Memory and Neural Computing
- Characterization and Applications of Magnetic Nanoparticles
- ZnO doping and properties
- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Multiferroics and related materials
- X-ray Diffraction in Crystallography
- Advanced Condensed Matter Physics
- Theoretical and Computational Physics
- Physics of Superconductivity and Magnetism
- Nuclear Materials and Properties
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Extraction and Separation Processes
- Iron oxide chemistry and applications
- Geological and Geochemical Analysis
- Magnetic Properties and Synthesis of Ferrites
- Transition Metal Oxide Nanomaterials
- Nuclear materials and radiation effects
- Nuclear reactor physics and engineering
- Ferroelectric and Piezoelectric Materials
- Surface and Thin Film Phenomena
- Advanced Materials Characterization Techniques
University of California, Davis
2016-2022
Helsinki Institute of Physics
2019
Tampere University
2019
Institute of Structure of Matter
2017
University of California, Berkeley
2012
Remanence magnetization plots (e.g., Henkel or δM plots) have been extensively used as a straightforward way to determine the presence and intensity of dipolar exchange interactions in assemblies magnetic nanoparticles single domain grains. Their evaluation is particularly important functional materials whose performance strongly affected by interparticle interactions, such patterned recording media nanostructured permanent magnets, well applications hyperthermia resonance imaging. Here, we...
Electric-field-controlled magnetism can boost energy efficiency in widespread applications. However, technologically, this effect is facing important challenges: mechanical failure strain-mediated piezoelectric/magnetostrictive devices, dearth of room-temperature multiferroics, or stringent thickness limitations electrically charged metallic films. Voltage-driven ionic motion (magneto-ionics) circumvents most these drawbacks while exhibiting interesting magnetoelectric phenomena....
Free-standing, interconnected metallic nanowire networks with density as low 40 mg/cm^{3} have been achieved over cm-scale areas, using electrodeposition into polycarbonate membranes that ion-tracked at multiple angles. Networks of magnetic nanowires further provide an exciting platform to explore 3-dimensional nanomagnetism, where their structure, topology and frustration may be used additional degrees freedom tailor the materials properties. New magnetization reversal mechanisms in cobalt...
Control of materials through custom design ionic distributions represents a powerful new approach to develop future technologies ranging from spintronic logic and memory devices energy storage. Perovskites have shown particular promise for due their high ion mobility sensitivity chemical stoichiometry. In this work, we demonstrate solid-state control in (La,Sr)CoO$_{3}$ thin films. Depositing Gd capping layer on the perovskite film, oxygen is controllably extracted structure, up-to 0.5...
Electrically induced ionic motion offers a new way to realize voltage-controlled magnetism, opening the door generation of logic, sensor, and data storage technologies. Here, we demonstrate an effective approach magneto-ionically electrically tune exchange bias in Gd/Ni1–xCoxO thin films (x = 0.50 0.67), where neither layers alone is ferromagnetic at room temperature. The Gd capping layer deposited onto antiferromagnetic Ni1–xCoxO initiates solid-state redox reaction that reduces interfacial...
Abstract The first order reversal curve (FORC) method is a magnetometry based technique used to capture nanoscale magnetic phase separation and interactions with macroscopic measurements using minor hysteresis loop analysis. This makes the FORC powerful tool in analysis of complex systems which cannot be effectively probed localized techniques. However, recovering quantitative details about identified phases can compared traditionally measured metrics remains an enigmatic challenge. We...
Due to its nonlocal nature, calculating the demagnetizing field remains biggest challenge in understanding domain structures ferromagnetic materials. Analytical descriptions of effects typically approximate walls as uniformly magnetized ellipsoids, neglecting both smooth rotation magnetization from one other and interaction between two domains. Here, instead field, we compute analytically energy a straight wall described by classical $tanh$ profile thin film with perpendicular magnetic...
Magnetic multilayer thin films with perpendicular magnetic anisotropy (PMA) and interfacial Dzyaloshinskii-Moriya interaction (iDMI) are of intense interest for realizing skyrmions modifying topological spin textures. We systematically investigate interlayer exchange coupling (IEC) in Pt/Co/Ru(Ir) superlattices that have PMA large iDMI. The IEC is greatly tunable by varying Ru(Ir) or Pt thickness the antiferromagnetic as $1.3\phantom{\rule{0.16em}{0ex}}\mathrm{mJ}/{\mathrm{m}}^{2}$ on same...
Complex oxide heterostructures provide access to emergent functional and structural phases which are not present in the bulk constituent materials. In this Rapid Communication, we focus on ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{CoO}}_{3}$ (LSCO)/Gd due high oxygen ion conductivity, as well coupled magnetic electronic properties of LSCO, strongly dependent stoichiometry. This combination enables ionic control LSCO thin films through presence getter layers such Gd. We utilize x-ray...
Solid state ionic approaches for modifying ion distributions in getter/oxide heterostructures offer exciting potentials to control material properties. Here we report a simple, scalable approach allowing total of the superconducting transition optimally doped YBa$_{2}$Cu$_{3}$O$_{7-{\delta}}$ (YBCO) films via chemically-driven migration mechanism. Using thin Gd capping layer up 20 nm deposited onto 100 thick epitaxial YBCO films, oxygen is found leach from deep within YBCO. Progressive...
Magnetization reversal of interconnected Kagome artificial spin ice was studied by the first-order curve (FORC) technique based on magneto-optical Kerr effect and magnetoresistance measurements. The magnetization exhibits a distinct six-fold symmetry with external field orientation. When is parallel to one nano-bar branches, domain nucleation/propagation annihilation processes sensitively depend cycling history maximum applied. nearly perpendicular FORC measurement reveals magnetic...
Magnetoelectric coupling in ferromagnet/multiferroic systems is often manifested the exchange bias effect, which may have combined contributions from multiple sources, such as domain walls, chemical defects or strain. In this study we magnetically "fingerprint" behavior of CoFe grown on epitaxial BiFeO3 (BFO) thin films by magnetometry and first-order-reversal-curves (FORC). The contribution to 71{\deg}, 109{\deg} charged ferroelectric walls (DWs) was elucidated FORC distribution. samples...
The first order reversal curve (FORC) method is a magnetometry based technique used to capture nanoscale magnetic phase separation and interactions with macroscopic measurements using minor hysteresis loop analysis. This makes the FORC powerful tool in analysis of complex systems which cannot be effectively probed localized techniques. However, recovering quantitative details about identified phases can compared traditionally measured metrics remains an enigmatic challenge. We demonstrate...
Magneto-ionics has shown promise to address the energy challenges in nanoelectronics, as materials properties may be manipulated by application of an electric field through controlled motion ions. Here we illustrate magneto-ionic control Dzyaloshinskii-Moriya interaction, chiral spin textures, exchange bias, and their potential applications 3-dimensional information storage.