A5014125151- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Anodic Oxide Films and Nanostructures
- Magnetism in coordination complexes
- Molecular Junctions and Nanostructures
- Advanced Condensed Matter Physics
- Organic Electronics and Photovoltaics
- Magnetic and transport properties of perovskites and related materials
- Transition Metal Oxide Nanomaterials
- Porphyrin and Phthalocyanine Chemistry
- Plasmonic and Surface Plasmon Research
- Superconductivity in MgB2 and Alloys
- Photonic and Optical Devices
- Advanced Memory and Neural Computing
- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Theoretical and Computational Physics
- Quantum and electron transport phenomena
- ZnO doping and properties
- Advanced Electron Microscopy Techniques and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Nonlinear Dynamics and Pattern Formation
- Superconducting Materials and Applications
- Laser-induced spectroscopy and plasma
- Surface Chemistry and Catalysis
General Atomics (United States)
2020-2024
Fusion Academy
2023
University of California, San Diego
2012-2022
The University of Texas at San Antonio
2016-2020
Institut de Ciència de Materials de Barcelona
2012-2017
Northwest Vista College
2017
Physical Sciences (United States)
2017
Universidad Nacional de Cuyo
2007-2008
Balseiro Institute
2007-2008
Comisión Nacional de Energía Atómica
2007-2008
We investigate guided vortex motion in high-temperature YBa${}_{2}$Cu${}_{3}$O${}_{7}$ thin films patterned with an array of asymmetric blind antidots. A preferential along spatial pinning potentials has been directly observed by changing the driving current direction. Transport measurements reveal that effective ratchet are created fixed vortices strongly pinned within antidots while asymmetry is transferred to interstitial vortices. study a novel system requires vortex-vortex interactions...
Phthalocyanines, a class of macrocyclic, square planar molecules, are extensively studied as semiconductor materials for chemical sensors, dye-sensitized solar cells, and other applications. In this study, we use angular dependent near-edge x-ray absorption fine structure (NEXAFS) spectroscopy quantitative probe the orientation electronic H2-, Fe-, Co-, Cu-phthalocyanine molecular thin films. NEXAFS measurements at both carbon nitrogen K-edges reveal that phthalocyanine films deposited on...
We present a variant of the template-assisted electrodeposition method that enables synthesis large arrays nanowires (NWs) on flat and curved substrates. This uses ultra-thin (50 nm-10 μm) anodic aluminum oxide membranes as template. have developed procedure two-polymer protective layer to transfer these templates onto almost any surface. applied this technique fabrication Ni segmented composition Ni/Au NWs silicon wafers, Cu tapes, thin (0.2 mm) wires. In all cases, complete coverage with...
Noninvasive manipulation of cell signaling is critical in basic neuroscience research and developing therapies for neurological disorders psychiatric conditions. Here, the wireless force-induced stimulation primary neuronal circuits through mechanotransduction mediated by magnetic microdiscs (MMDs) under applied low-intensity low-frequency alternating fields (AMFs), described. MMDs are fabricated top-down lithography techniques that allow cost-effective mass production biocompatible with...
Strain-induced self-assembled La0.7Sr0.3MnO3 nanoislands of lateral size 50−150 nm and height 10−40 have been grown on yttria-stabilized zirconia (001)-substrates from ultradiluted chemical solutions based metal propionates. The grow highly relaxed withstanding the epitaxial relation (001)LSMO[110]//(001)YSZ[010] show bulk-like average magnetic properties in terms Curie temperature saturation magnetization. interplay magnetocrystalline shape anisotropy within nanoisland ensemble results an...
Conventional immunosensors typically rely on passive diffusion dominated transport of analytes for binding reaction and hence, it is limited by low sensitivity long detection times. We report a simple efficient impedance sensing method that can be utilized to overcome both limitations immunosensors. This incorporates the structural advantage nanorod-covered interdigitated electrodes microstirring effect AC electrothermal flow (ACET) with spectroscopy. ACET induced biased electric field...
Superconductivity and ferromagnetism are two antagonistic phenomena that combined can lead to a rich phenomenology of interactions, resulting in novel physical properties unique functionalities. Here we propose an original hybrid system formed by high-temperature superconducting film, patterned with antidots, ferromagnetic nano-rods grown inside them. This particular structure exhibits the synergic influence superconductor (SC) - (FM) stray fields, both behaviour film three-dimensional (3D)...
A study of the electromagnetic response superconductor/ferromagnet $\mathrm{Nb}∕\mathrm{Co}$ superlattices is presented. The dc magnetization measured as a function Co layer thickness, applied field ${H}_{a}$, and temperature. For very thin layers, no ferromagnetism detected observed essentially that collection uncoupled Nb layers. When thick enough for to be established, prior field-cooled measurements, layers are magnetically saturated in parallel or antiparallel directions ${H}_{a}$. In...
The growing need for biomedical contrast agents has led to the current development of multi-functional materials such as lanthanide-based nanoparticles (NPs). optical and magnetic properties these (NPs) possess are important enhance imaging techniques. To increase emissions nanoparticles, neodymium (Nd3+) ytterbium (Yb3+) were introduced into a host NaGdF4. energy transfer between Nd3+ Yb3+ was then investigated at multiple concentrations determine optimal dopant levels. NaGdF4:Nd3+,Yb3+...
Magnetization measurements in superconductor/ferromagnet Nb/Co superlattices show a complex behavior as function of temperature, applied field and sample history. In base to simple model it is shown that this due an interplay between the superconductor magnetization temperature dependence, ferromagnet time stray fields both materials. It also magnetic state Co layers modified by Nb superconducting response, implying problem superconductor/ferromagnetic heterogeneous has be solved...
We present a software package called Microscopy Image Segmentation Tool (MIST). MIST is designed for analysis of microscopy images which contain large collections small regions interest (ROIs). Originally developed porous anodic alumina scanning electron images, capabilities have been expanded to allow use in variety problems including biological tissue, inorganic and organic film grain structure, as well nano- meso-scopic structures. provides robust segmentation algorithm the ROIs, includes...
Rectified flux motion arising from the collective effect of many interacting vortices is obtained in a specially designed superconducting device. Ratchet structures with different asymmetric pinning potentials are generated by tuning size, depth, and distribution triangular blind-antidots high-temperature film. We experimentally theoretically demonstrate that amplitude sign rectified vortex can be finely tuned pattern geometry. Two dynamical regimes depending on nature initiating dissipation...
We study the effect of photodiode angular response on measurement surface plasmon resonance (SPR) in metallic thin films using Kretschmann-Raether configuration. The signal depends not only light intensity but also incidence angle. This implies that sensitivity changes along SPR curve. Consequently, measured spectrum is distorted, thus affecting fits and numerical analyses curves. analyze magnitude this change, determine when it significant, develop a calibration method experimental setup...
Sub-100 nm ferromagnetic/antiferromagnetic nanodisks present enhanced magnetic properties with respect to their thin film counterparts. Co/CoO disks were fabricated over large areas by a transferring process of an anodic aluminum oxide membrane, electron beam evaporation Co, and subsequent oxidation CoO. This method reveals exchange bias fields up 4 times larger than that in films higher blocking temperatures for the same protocol. The significant improvement is attributed finite-size...
The transport properties of metallophthalocyanine thin films are important ingredients in many technological applications. Ohmic conductance film (15 nm to 90 nm) Co-phthalocyanine (CoPc) capacitive devices has been investigated the temperature range 40 K 300 K. For Pd and V electrodes, electrode-film (E-F) interface metallic micro-shorts contribute substantially with decrease CoPc layer thickness. A quantitative model which describes E-F interface, roughness, micro-shorts, exponential...
We present an experimental setup for the simultaneous measurement of surface plasmon resonance (SPR) and x-ray absorption spectroscopy (XAS) on metallic thin films at a synchrotron beamline. The system allows measuring in situ real time effect irradiation SPR curves to explore interaction x-rays with matter. It is also possible record XAS spectra while exciting order study changes induced by excitation plasmons. Combined experiments recording simultaneously scanning different parameters can...
Magnetic nanostructures of different size, shape, and composition possess a great potential to improve current technologies like data storage electromagnetic sensing. In thin ferromagnetic nanowires, their magnetization behavior is dominated by the competition between magnetocrystalline anisotropy (related crystalline structure) shape anisotropy. this way electron diffraction methods precession (PED) can be used link magnetic observed Electron Holography (EH) with its crystallinity. Using...
We present a comparative study of vortex pinning efficiency in superconducting (V) thin films grown on two similar triangular arrays (Nb) and nonsuperconducting (Cu) nanodots. Resistance magnetization anomalies at the same matching fields confirm periodicity both samples. However, we found distinct features: First, sample with dots shows stronger that appears as sharper peaks loops higher critical current density larger field low temperatures. Second, an overall increase resistance V film Nb...
We present a Surface Plasmon Resonance spectroscopy study of Co-Phthalocyanine (CoPc) thin films grown on Au layers at different substrate temperatures. demonstrate that for quantitative analysis, fitting the resonance angle alone is insufficient and Whole Curve Analysis (WCA) needs to be performed. This because CoPc film dielectric constant thickness are strongly affected by temperature, even when total deposited mass remains fixed. Using WCA, we able uniquely fit both constants thicknesses...
W-SiC composite material is a promising plasma-facing candidate alternative to pure W due the low neutron activation, impurity radiation, and tritium diffusivity of SiC while leveraging high erosion resistance armor. Additionally, have thermomechanical compatibility given their similar thermal expansion rates. The present study addresses synthesis performance compositionally graded films fabricated by pulsed-DC magnetron sputtering. Compositional gradients were characterized using...
We have studied the influence of controlled defects on magnetic properties La0.67Sr0.33MnO3 (LSMO) thin films. used 100 nm thick epitaxial LSMO films, which were grown SrTiO3 substrates and introduced stoichiometry changes using oxygen ion irradiation through nanoporous alumina masks. Oxygen mask creates cascades in spatially-modulated regions plane film. The samples compared before after irradiation. found that reduces ferromagnetic ordering temperature, decreases total magnetization,...