A5103247126- Transition Metal Oxide Nanomaterials
- ZnO doping and properties
- Gas Sensing Nanomaterials and Sensors
- Ga2O3 and related materials
- Magnetic properties of thin films
- Advanced Memory and Neural Computing
- Metamaterials and Metasurfaces Applications
- Advanced Antenna and Metasurface Technologies
- Magnetic and transport properties of perovskites and related materials
- Perovskite Materials and Applications
- Chalcogenide Semiconductor Thin Films
- Catalysis and Oxidation Reactions
- Antenna Design and Analysis
- Advanced Condensed Matter Physics
- Electron and X-Ray Spectroscopy Techniques
- Multiferroics and related materials
- Magnetic Properties and Applications
- solar cell performance optimization
- Integrated Circuits and Semiconductor Failure Analysis
- Magneto-Optical Properties and Applications
- Heusler alloys: electronic and magnetic properties
- Magnetic Properties and Synthesis of Ferrites
- Copper-based nanomaterials and applications
- Quantum and electron transport phenomena
- Semiconductor materials and devices
University of South Alabama
2023
University of California, San Diego
2010-2017
University of Virginia
2008-2017
SensorMetrix (United States)
2015-2016
Abstract Radiation‐resistant but cost‐efficient, flexible, and ultralight solar sheets with high specific power (W g −1 ) are the “holy grail” of new space revolution, powering private exploration, low‐cost missions, future habitats on Moon Mars. Herein, this study investigates an all‐perovskite tandem photovoltaic (PV) technology that uses ultrathin active layer (1.56 µm) offers conversion efficiency, discusses its potential for high‐specific‐power applications. This demonstrates tandems...
Using a novel growth technique called reactive bias target ion beam deposition, the authors have prepared highly oriented VO2 thin films on Al2O3 (0001) substrates at various temperatures ranging from 250to550°C. The influence of parameters microstructure and transport properties was systematically investigated. A change in electrical conductivity 103 measured 341K associated with well known metal-insulator transition (MIT). It observed that MIT temperature can be tuned to higher by mixing...
Metamaterial absorbers have been demonstrated across much of the electromagnetic spectrum and exhibit both broad narrow-band absorption for normally incident radiation. Absorption diminishes increasing angles incidence transverse electric polarization falls off more rapidly than magnetic. We unambiguously demonstrate that broad-angle TM behavior cannot be associated with periodicity, but rather is due to coupling a surface mode supported by, well described via effective optical constants...
We use THz time-domain spectroscopy to investigate the far-infrared properties of vanadium dioxide thin films, strain-engineered through epitaxial growth on (100)R TiO2 substrates. The films exhibit a large uniaxial tensile strain along rutile c-axis. X-ray diffraction measurements reveal structural transition temperature 340 K, whereas independent conductivity yield metal–insulator 365 K cR. Analysis these results suggests Mott–Hubbard behavior cR-axis. Along cR is approximately 5500 (Ω...
Epitaxial strain can play an important role in controlling the local phase dynamics of transition metal oxides. With scattering-type scanning near-field optical microscopy, we visualize three dimensional landscape inhomogeneity strained VO2 films grown on [100]R TiO2 substrates. We demonstrate that different symmetries are spontaneously broken vicinity transition: (1) Monoclinic-tetragonal (rutile) crystal symmetry breaking due to structural transition, (2) in-plane (x-y plane) rotational...
In this letter, we discuss the design, fabrication, and experimental characterization of a bi-layer fully functional near-perfect metamaterial absorber (MMA) in long-wavelength infrared (LWIR), which is broadband generally insensitive to polarization up 60° incidence angle. A spectral absorptance ≥99% was attained simultaneously at multiple LWIR wavelengths, with bandwidth 2 μm where ≥90%. This remarkable behavior attributed strong mixing coupling modes between two resonators ground plane...
Ultrafast optical pump--optical probe and pump--terahertz spectroscopy were performed on vanadium dioxide (${\mathrm{VO}}_{2}$) sesquioxide (${\mathrm{V}}_{2}{\mathrm{O}}_{3}$) thin films over a wide temperature range. A comparison of the experimental data from these two different techniques oxides, in particular spectral weight oscillations generated by photoinduced longitudinal acoustic modulation, reveals strong electron-phonon coupling that exists both materials. The low-energy Drude...
In this letter, we reported a very large anisotropy in dc conductivity of epitaxial VO2 thin films deposited on (011) TiO2 substrate. The film grew epitaxially and x-ray diffraction showed that had the tetragonal symmetry due to substrate clamping effect at room temperature. There was compressive strain −1.2% along c-axis rutile VO2. We observed strong angular dependence in-plane conductivity. calculated σ1/σ3∼5.14, which anomalously large. attributed drastic increase clamping. This...
Co Fe ∕ Mn , FeMn∕CoFe bilayers and CoFe∕FeMn∕CoFe trilayers were grown in magnetic field at room temperature. The exchange bias HEB depends strongly on the order of depositions is much higher CoFe∕FeMn than interfaces. By combining two bilayer structures into symmetric CoFe∕FeMn(tFeMn)∕CoFe trilayers, HEBt HEBb top bottom CoFe layers, respectively, are both enhanced. Reducing tFeMn also results enhancements HEBt. These evidence propagation between interfaces mediated by FeMn antiferromagnetic order.
We present a study of the exchange bias in different configurations V2O3 thin films with ferromagnetic layers. The is accompanied by large vertical shift magnetization. These effects are only observed when grown on top Ni80Fe20 permalloy. magnitude as 60% total magnetization which has never been reported any system. X-Ray diffraction studies show that growth conditions promote formation ferrimagnetic Fe3O4 interlayer. change easy axis across Verwey transition at 120 K correlated appearance...
Chromium dioxide (CrO2) is a half metal that of interest for spintronic devices. It has not been synthesized through traditional physical vapor deposition (PVD) techniques because its thermodynamic instability in low oxygen pressures. Epitaxial thin films Ru doped tetragonal rutile CrO2 were by PVD technique. The as-deposited RuxCr1−xO2 was ferrimagnetic with the saturation magnetization moment showing strong dependence on concentration. Curie temperature as high 241 K obtained ∼23 at. % Ru....
We report on peculiar magnetic hysteresis behavior of Ru0.25Cr0.75O2 thin films. describe three unusual phenomena inherent to this material; (i) intrinsic positive exchange bias in a single phase epitaxial film ferrimagnet with the absence clear and distinct magnetic-magnetic interface, (ii) field modulation shifted M(H) loop along axis direction, (iii) inverted loops which overall area is nearly zero over entire cycle. These results can be understood within context very interface TiO2 (001)...
Abstract Spectral response measurements of germanium‐based triple‐junction solar cells were performed under a variety light and voltage bias conditions. Two the three junctions exhibited bias‐dependent artifacts in their measured responses, complicating true spectral these junctions. To obtain more insight into observed phenomena, set current‐voltage measurement combinations also on identical illumination conditions, data used context diode‐based analytical model to calculate predict...
Magnetic tunnel junctions (MTJs) with an AlOx barrier were fabricated by a biased target ion beam deposition (BTIBD) sputtering technique using low energy source (0–50 eV) and voltage targets. The BTIBD system applies bias directly onto the desired targets, providing enough avoiding overspill contamination during film deposition. successful of AlOx-MTJs demonstrated capability to make multilayer structures good quality. MTJ thin surface roughness intermixing between layers are among key...
Photovoltaics In article number 2102246 Felix Lang, Giles E. Eperon, Samuel D. Stranks and co-workers investigate efficient all perovskite-based tandem photovoltaics. This class of photovoltaics combine high specific power with good tolerance to the harsh radiation environment in space, thereby promising a next-generation lightweight cost-efficient solutions private space exploration, low-cost missions as well future habitats on Moon Mars.
We probe the temperature dependent far-infrared conductivity of highly strained (100) and (110) VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thin films using THz Time Domain Spectroscopy. Large in-plane anisotropy is observed in both metallic metal-insulator transition temperature.
We probe the temperature dependent far-infrared conductivity of highly strained (100)VO2 thin films using THz TDS. A large in-plane anisotropy is observed in both metallic and metal-insulator transition temperature.