Search results for "Applied Physics"
showing 10 items of 1226 documents
First-principles LCAO study of the low and room temperature phases of CdPS$_3$
2020
A.K. is grateful to the Latvian Council of Science project no. lzp-2018/2-0353 for financial support. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.
Thickness-dependent electron momentum relaxation times in iron films
2020
Terahertz time-domain conductivity measurements in 2 to 100 nm thick iron films resolve the femtosecond time delay between applied electric fields and resulting currents. This current response time decreases from 29 fs for thickest films to 7 fs for the thinnest films. The macroscopic response time is not strictly proportional to the conductivity. This excludes the existence of a single relaxation time universal for all conduction electrons. We must assume a distribution of microscopic momentum relaxation times. The macroscopic response time depends on average and variation of this distribution; the observed deviation between response time and conductivity scaling corresponds to the scaling…
EPR characterization of erbium in glasses and glass ceramics
2020
Electron paramagnetic resonance (EPR) is a well-established spectroscopic technique for electronic structure characterization of rare-earth ion impurities in crystalline and amorphous hosts. EPR spectra of erbium-doped glass matrices and nanocomposites can provide information about local structure variations induced by changes in chemical composition or crystallization processes. Characterization possibilities of Er3+ ions in glasses and glass ceramics including direct EPR measurements, indirect investigations via secondary paramagnetic probes, and optically detected magnetic resonance techniques are considered in this article. ----/ / /---- This is the pre-print of the following article: A…
In-situ small-angle x-ray scattering study of nanoparticles in the plasma plume induced by pulsed laser irradiation of metallic targets
2012
Import JabRef; International audience; Small angle x-ray scattering was used to probe in-situ the formation of nanoparticles in the plasma plume generated by pulsed laser irradiation of a titanium metal surface under atmospheric conditions. The size and morphology of the nanoparticles were characterized as function of laser irradiance. Two families of nanoparticles were identified with sizes on the order of 10 and 70 nm, respectively. These results were confirmed by ex-situ transmission electron microscopy experiments.
Blistering mechanisms of atomic-layer-deposited AlN and Al2O3 films
2017
Blistering of protective, structural, and functional coatings is a reliability risk pestering films ranging from elemental to ceramic ones. The driving force behind blistering comes from either excess hydrogen at the film-substrate interface or stress-driven buckling. Contrary to the stress-driven mechanism, the hydrogen-initiated one is poorly understood. Recently, it was shown that in the bulk Al-Al2O3 system, the blistering is preceded by the formation of nano-sized cavities on the substrate. The stress-and hydrogen-driven mechanisms in atomic-layer-deposited (ALD) films are explored here. We clarify issues in the hydrogen-related mechanism via high-resolution microscopy and show that at…
Antenna-coupled spintronic terahertz emitters driven by a 1550 nm femtosecond laser oscillator
2019
We demonstrate antenna-coupled spintronic terahertz (THz) emitters excited by 1550 nm, 90 fs laser pulses. Antennas are employed to optimize THz outcoupling and frequency coverage of ferromagnetic/nonmagnetic metallic spintronic structures. We directly compare the antenna-coupled devices to those without antennas. Using a 200 μm H-dipole antenna and an ErAs:InGaAs photoconductive receiver, we obtain a 2.42-fold larger THz peak-peak signal, a bandwidth of 4.5 THz, and an increase in the peak dynamic range (DNR) from 53 dB to 65 dB. A 25 μm slotline antenna offered 5 dB larger peak DNR and a bandwidth of 5 THz. For all measurements, we use a comparatively low laser power of 45 mW from a comme…
Enhanced operational stability through interfacial modification by active encapsulation of perovskite solar cells
2020
Encapsulates are, in general, the passive components of any photovoltaic device that provides the required shielding from the externally stimulated degradation. Here we provide comprehensive physical insight depicting a rather non-trivial active nature, in contrast to the supposedly passive, atomic layer deposition (ALD) grown Al2O3 encapsulate layer on the hybrid perovskite [(FA0.83MA0.17)0.95Cs0.05PbI2.5Br0.5] photovoltaic device having the configuration: glass/FTO/SnO2/perovskite/spiro-OMeTAD/Au/(±) Al2O3. By combining various electrical characterization techniques, our experimental observations indicate that the ALD chemistry produces considerable enhancement of the electronic conductiv…
Optical investigation of the OH− groups in the LiNbO3 doped by copper
2019
Doping ions and OH− groups absorption bands spatial profiles were investigated for the case of congruent LiNbO3 single crystal grown by Czochralski technique. Doping was performed after the crystal...
Thermo-optic control of dielectric-loaded plasmonic Mach-Zehnder interferometers and directional coupler switches
2012
We report detailed experimental studies of compact fiber-coupled dielectric-loaded plasmonic waveguide components-Mach-Zehnder interferometers (MZIs) and directional couplers (DCs)-whose operation at telecom wavelengths is controlled via the thermo-optic effect by electrically heating the gold stripe of dielectric-loaded plasmonic waveguides. The effect of the gaps isolating the heated part of the waveguide from the rest of the structure was examined showing the presence of a Fabry-Perot cavity in this MZI arm. Wavelength-dependent modulation is demonstrated with MZI-based components, and wavelength dependent low power (similar to 0.92 mW) rerouting is achieved with DC switches. Furthermore…
High-temperature X-ray absorption spectroscopy study of thermochromic copper molybdate
2019
Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2017/5 and SJZ/2018/1 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. The work was also supported by philanthropist MikroTik and administrated by the University of Latvia Foundation . The experiment at the Elettra synchrotron was performed within the project No. 20150303 .