A5071555016- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Transition Metal Oxide Nanomaterials
- Magnetic Properties and Applications
- Theoretical and Computational Physics
- Advanced Memory and Neural Computing
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Surface and Thin Film Phenomena
- Quantum and electron transport phenomena
- ZnO doping and properties
- Characterization and Applications of Magnetic Nanoparticles
- Electronic and Structural Properties of Oxides
- Superconductivity in MgB2 and Alloys
- Copper Interconnects and Reliability
- Superconducting Materials and Applications
- Magneto-Optical Properties and Applications
- Gas Sensing Nanomaterials and Sensors
- Magnetic Properties of Alloys
- Semiconductor materials and devices
- Metal and Thin Film Mechanics
- nanoparticles nucleation surface interactions
- Iron-based superconductors research
- Advanced Chemical Physics Studies
- Rare-earth and actinide compounds
University of California, San Diego
2016-2025
Materials Science & Engineering
2025
University of California, Los Angeles
1977-2021
Ikerbasque
2015-2020
Basque Center for Materials, Applications and Nanostructures
2015-2020
University of the Basque Country
2015-2020
Technion – Israel Institute of Technology
2020
Universidad Católica Santo Domingo
2009-2018
Northrop Grumman (United States)
2018
Weatherford College
2017
In situ neutron powder diffraction measurements show that the orthorhombic-to-tetragonal phase transition in $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}$, which occurs near 700\ifmmode^\circ\else\textdegree\fi{}C a pure oxygen atmosphere, is an order-disorder disordering of atoms into normally vacant site destroys one-dimensional Cu-O chains present room-temperature orthorhombic structure. For both structures, stoichiometry decreases monotonically with...
This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic phenomena associated with spin-orbit coupling intrinsic symmetry breaking at interfaces. It provides a historical background literature survey, but focuses recent progress, identifying the most exciting new scientific results pointing to promising future research directions. starts an introduction overview of how basic properties are affected by interfaces, then turns...
We present a general procedure for quantitative structural refinement of superlattice structures. To analyze wide range superlattices, we derived kinematical diffraction formula that includes random, continuous, and discrete fluctuations from the average structure. show only structure factor one single layer each material has to be averaged over random variables prove this relation is equivalent earlier, less models. Implementing nonlinear-fitting algorithm fit entire x-ray-diffraction...
We have determined the crystal structure of single-phase stoichiometric high-temperature superconductor in Y-Ba-Cu-O system using high-resolution neutron powder diffraction. This compound has an orthorhombic with space group Pmmm and lattice constants a=3.8231 Å, b=3.8864 c=11.6807 Å. The consists ‘‘dimpled’’ CuO2 layers a-b planes loosely bonded by one-dimensional fencelike square-planar CuO3 chains b-c planes.
A new class of layered materials has been prepared by alternate deposition two dissimilar metals. Strong experimental evidence is shown that coherent structures with layer thicknesses approaching interatomic spacing can be in this fashion. The x-ray measurements are found to good qualitative and quantitative agreement model calculations.
We have discovered a positive unidirectional exchange anisotropy in antiferromagnetic (Fe${\mathrm{F}}_{2}$) and ferromagnetic (Fe) bilayers cooled through the critical temperature ${T}_{N}$ large magnetic fields. For low cooling fields, ferromagnet's magnetization ( $M\ensuremath{-}H$) loop center shifts to negative as is normally observed other systems. In contrast, fields can cause shift be positive. This explained if Fe${\mathrm{F}}_{2}$ surface spins couple external field above...
Triangular arrays of submicrometer magnetic dots, with typical spacing 400--600 nm and diameters close to 200 nm, have been fabricated by electron beam lithography study pinning effects on Nb thin films. The resistivity versus field curves exhibit regular structure. Minima appear at constant intervals, given the lattice parameter dot array. angular, current, temperature dependencies imply synchronized array which is relevant high vortex velocities, when order in increases.
We have performed detailed studies of the structure, magnetotransport, and magnetization Fe/Cr superlattices as a function systematic changes in interfacial roughness. The results clearly show that giant magnetoresistance is enhanced by presence This fact indicates roughness should be explicitly included theoretical calculations experimental characterization exhibiting magnetoresistance.
Measurements of the superconducting critical temperature ${\mathrm{T}}_{\mathrm{c}}$ are reported for (${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{x}\mathrm{\ensuremath{-}}\mathit{y}}$${\mathrm{Ca}}_{\mathit{y}}$)${\mathrm{Pr}}_{\mathit{x}}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ system as a function x and y. The ${\mathit{T}}_{\mathit{c}}$ vs c curves at fixed values can be resolved into two contributions: (1)...
We show that the main mechanism for dc voltage or current induced insulator-metal transition in vanadium dioxide VO(2) is due to local Joule heating and not a purely electronic effect. This "tour de force" experiment was accomplished by using fluorescence spectra of rare-earth doped micron sized particles as temperature sensors. As current, reaches indicating plays predominant role. has critical implications understanding direct impact on applications which use externally drive transition.
This tutorial describes challenges and possible avenues for the implementation of components a solid-state system, which emulates biological brain. The is devoted mostly to charge-based (i.e. electric controlled) using transition metal oxide materials, exhibit unique properties that emulate key functionalities needed this application. In Sec. I, we compare main differences between conventional computational machine, based on Turing-von Neumann paradigm, neuromorphic tries important We also...
Abstract CMOS-RRAM integration holds great promise for low energy and high throughput neuromorphic computing. However, most RRAM technologies relying on filamentary switching suffer from variations noise, leading to computational accuracy loss, increased consumption, overhead by expensive program verify schemes. We developed a filament-free, bulk technology address these challenges. systematically engineered trilayer metal-oxide stack investigated the characteristics of with varying...
Polarized neutron reflectometry is used to probe the in-plane projection of net-magnetization vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{M}}$ polycrystalline Fe films exchange coupled twinned (110) $\mathrm{MnF}{}_{2}$ or $\mathrm{FeF}{}_{2}$ antiferromagnetic (AF) layers. The magnetization reversal mechanism depends upon orientation cooling field with respect microstructure AF, and whether applied increased (or decreased from) a positive saturating field; i.e., asymmetric. sample...
The sensitivities of metallophthalocyanine (MPcs: M = Co, Ni, Cu, Zn, and H2) chemiresistors to vapor phase electron donors were examined using 50 nm MPc films deposited on interdigitated electrodes. Sensor responses measured as changes in current at constant voltage. Analytes chosen span a broad range Lewis base hydrogen bond strengths. sensor correlated exponentially with binding enthalpy. These exponential fits consistent the van't Hoff equation standard free energy relationships....
We report the temperature and cooling field dependence of coercivity exchange biased ${\mathrm{MnF}}_{2}/\mathrm{Fe}$ bilayers. When antiferromagnetic surface is in a state maximum magnetic frustration net bias zero, we observe strong enhancement coercivity, which proportional to coupling between layers. Hence, can be tuned reproducible repeatable fashion same sample. propose that frustrated interface provides local energy minima effectively pin propagating domain walls ferromagnet, leading...
The induced moment in antiferromagnetic (AFM)--ferromagnetic (FM) $({\mathrm{FeF}}_{2}\ensuremath{-}\mathrm{Fe}$ and ${\mathrm{MnF}}_{2}\ensuremath{-}\mathrm{Fe})$ bilayers has been studied from the shift along magnetization axis of exchange-biased hysteresis loops. depends strongly on cooling field microstructure AFM layer. for small fields can be opposite to field, indicating that, some cases, presence FM layer induces an coupling at interface. Samples with negative shifts...
We have calculated the energy distributions of sputtered Nb and Cu atoms ejected from amorphous targets under low-energy Ar bombardment. A formula based on elementary kinetic gas theory is used to calculate subsequent loss due collisions in sputtering gas. The arriving at substrate compared with obtained using thermal evaporation techniques. This comparison indicates that preparation epitaxial metallic films, such as Layered Ultrathin Coherent Structures techniques may fundamental advantages...
Metallic superlattices of nickel and molybdenum have been synthesized for a wide range layer thicknesses by alternate sputtering. X-ray examination shows that they are composed layers fcc bcc oriented along [111] [110] directions, respectively. Anomalies observed in the lattice spacings, elastic moduli, electrical resistivity versus modulation wavelength. These anomalies occur simultaneously at same superlattice The interpreted as due to strains lattice.