Hot carriers generated from the nonradiative decay of localized surface plasmons are capable driving charge-transfer reactions at surfaces metal nanostructures. Photocatalytic devices utilizing plasmonic hot often based on nanoparticle/semiconductor heterostructures owing to their efficient electron–hole separation ability. The rapid thermalization nanoparticles yields a distribution carrier energies that determines capability photocatalytic device drive redox reactions. Here, we quantify...

Abstract Atomic-scale intrinsic defects play a key role in controlling functional electronic properties of two-dimensional (2D) materials. Here, we present low-temperature scanning–tunneling microscopy and spectroscopy investigation common point-defect monolayer molybdenum disulfide (MoS 2 ). We employ sample preparation method which the film surface is never exposed to air so that native dangling bonds surrounding are preserved. Molybdenum vacancies identified by their three characteristic...

The effect of dimensional confinement on the optical band gap SrTiO3 is investigated by periodically introducing one extra SrO monolayer every n layers. result = 1–5 and 10 members Srn+1TinO3n+1 Ruddlesden-Popper homologous series. Spectroscopic ellipsometry, transmission, cathodoluminescence measurements reveal these phases to have indirect gaps at room temperature with values that decrease monotonically increasing n. First-principles calculations suggest as increases TiO6 octahedra become...

A plasmonic analogue of electromagnetically induced transparency is activated and tuned in the terahertz (THz) range asymmetric metamaterials fabricated from high critical temperature (Tc) superconductor thin films. The design provides a near-field coupling between superradiant subradiant mode, which has been widely through superconductivity monitored by Fourier transform infrared spectroscopy. sharp window that appears extinction spectrum exhibits relative modulation up to 50% change....

We report on structural and electronic properties of defects in chemical vapor-deposited monolayer few-layer MoS2 films. Scanning tunneling microscopy, Kelvin probe force transmission electron microscopy were used to obtain high resolution images quantitative measurements the local density states, work function nature track evolution that are formed under heating beam irradiation. observe formation metastable domains with different values after annealing material ultra-high vacuum moderate...

Proximity effects in superconducting normal (SN) material heterostructures with metals and semiconductors have long been observed theoretically described terms of Cooper pair wave functions Andreev reflections. Whereas the semiconducting N-layer materials proximity experiments to date doped tens nanometers thick, we present here a tunneling study involving pristine single-layer transition-metal dichalcogenide film MoS2 placed on top Pb thin film. Scanning microscopy spectroscopy together...

We have measured the normal state temperature dependence of Hall effect and magnetoresistance in epitaxial ${\mathrm{MgB}}_{2}$ thin films with variable disorders characterized by residual resistance ratio $RRR$ ranging from 4.0 to 33.3. A strong nonlinearity been found clean samples, they decrease gradually increase or temperature. By fitting data theoretical model based on Boltzmann equation ab initio calculations for a four-band system, first time, we derived scattering rates these four...

The ability to control nanoscale electronic properties by introducing macroscopic strain is of critical importance for the implementation two-dimensional (2D) materials into flexible electronics and next-generation engineering devices. In this work, we correlate atomic-scale lattice deformation with a systematic bending monolayer molybdenum disulfide films using scanning tunneling microscopy spectroscopy implemented custom-built sample holder strain. Using technique, are able induce strains...

Recent results of Raman spectroscopy studies lattice dynamics and phase transitions in ferroelectric thin films superlattices are reviewed. SrTiO 3 , BaTiO Ba x Sr 1− TiO comparison with corresponding single crystals presented; essential differences the behavior discussed. Application ultraviolet for nanoscale heterostructures, such as /SrTiO superlattices, is demonstrated.

The effect of stoichiometry on the dielectric properties and soft mode behavior strained epitaxial Sr1+xTiO3+δ films grown DyScO3 substrates is reported. Direct comparisons between nominally stoichiometric non-stoichiometric have been performed through measurements lattice parameters, temperature-dependent permittivities, second harmonic generation, terahertz spectra. film shows dispersion-free low-frequency permittivity with a sharp maximum pronounced behavior. Our results suggest that...

We studied the phase transitions, domain morphologies, and polarizations in BaTiO3∕SrTiO3 superlattices grown on SrTiO3 substrates. Using field approach, we discovered remarkable influence of film/substrate interfacial coherency ferroelectricity layers within a superlattice: it is an orthorhombic ferroelectric for incoherent interface while exhibits only induced polarization by adjacent BaTiO3 coherent interface. presented morphologies individual which have different symmetries. The results...

We have fabricated planar thin-film MgB2 Josephson junctions and 20-junction series arrays using 200-keV ion implantation electron-beam lithography. Resistively shunted junction I-V characteristics were observed in the temperature range of 34–38K. The ac effect was flat giant Shapiro steps suggest good uniformity with a small spread parameters. dependence critical current suggests that nature interface between superconductor normal region can be described soft boundary proximity coupling...

Phase pure and clean MgB2 films have been fabricated on different types of single-crystal substrate, including SiC, sapphire, MgO, LaAlO3, SrTiO3, yttrium-stabilized ZrO2 (YSZ), via the hybrid physical–chemical vapor deposition (HPCVD) technique. Pure with structural textures are obtained by selecting substrate its orientation, such as off-axis epitaxial MgO(211) or textured YSZ(110) substrates. Films show Tc(0) in range 37–41 K, residual resistivity ρ(42 K) between 0.3 5 µΩ cm film...

Oxide heterostructure superlattices constitute a new family of materials with tunable ferroelectric properties. While theoretical models predict the presence nanosized domains in these films, they had not been observed as magnitude response functions challenges limits experimental detection. Here, protocol precise variant piezoforce microscopy is used to image BaTiO(3)/SrTiO(3) superlattices. Comparison experimentally determined polarization predictions phase-field calculations quantitative...

Hot-Electron Bolometer (HEB) mixers have proven to be the best tool for high-resolution spectroscopy at Terahertz frequencies. However, current state of art NbN suffer from a small intermediate frequency (IF) bandwidth as well low operating temperature. MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is promising material HEB mixer technology in view its high critical temperature and fast thermal relaxation allowing large IF...

Hot-electron bolometer mixers employing thin films of conventional superconducting materials have already been successfully fabricated in the past. Magnesium diboride (MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) is a promising alternative to superconductors, and we report fabrication study ultrathin MgB down 10 nm deposited by hybrid physical-chemical vapor deposition technique. The showed T...

The current-voltage $(I\text{\ensuremath{-}}V)$ characteristics of various $\mathrm{Mg}{\mathrm{B}}_{2}$ films have been studied at different magnetic fields parallel to the $c$ axis. At ${\ensuremath{\mu}}_{0}H$ between 0 and $5\phantom{\rule{0.3em}{0ex}}\mathrm{T}$, vortex liquid-glass transitions were found in $I\text{\ensuremath{-}}V$ isotherms. Consistently, curves measured temperatures show a scaling behavior framework quasi-two-dimension (quasi-2D) vortex-glass theory. However,...

We have fabricated series arrays of closely spaced planar Josephson junctions on MgB2 films using a 30 keV focused helium ion beam. Uniformity junction parameters within the is sufficient for achieving phase-lock into an applied microwave signal, and flat giant Shapiro steps are observed. The spread in critical current 60-Josephson array estimated to be less than 3.5%, significantly better reported by other techniques. These results demonstrate potential He <sup...

A localized measurement of the RF critical field on superconducting radio frequency (SRF) cavity materials is a key step to identify specific defects that produce quenches SRF cavities. Two measurements are performed demonstrate these capabilities with near-field scanning probe microwave microscope. The first third harmonic nonlinear high Residual-Resistance-Ratio bulk Nb sample showing strong response, surface magnetic Bsurface∼102 mT. second raster scanned response image MgB2 thin film...

A series of LaAlO3 thin films with different thicknesses were deposited by pulsed laser deposition at temperatures from 720 °C to 800 °C. The results grazing incidence x-ray diffraction and reciprocal space mapping indicate that a layer adjacent the SrTiO3 substrate remains almost coherently strained substrate, while top starts relax quickly above certain critical thickness, followed gradual relaxation larger film thickness when they are grown lower temperatures. atomic force microscopy show...

Magnesium diboride (MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) is considered a candidate for the next generation superconducting radio frequency (SRF) cavities due to its higher critical temperature T xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> (40 K) and increased superheating field (H xmlns:xlink="http://www.w3.org/1999/xlink">sh</sub> compared other conventional superconductors. These properties can lead reduced BCS...

Terahertz high-resolution spectroscopy of interstellar molecular clouds greatly relies on hot-electron superconducting bolometric (HEB) mixers. Current state-of-the-art receivers use mixer devices made from ultrathin (~ 3-5 nm) films NbN with critical temperature ~ 9-11 K. Such mixers have been deployed a number groundbased, suborbital, and orbital platforms including the HIFI instrument Hershel Space Observatory. Despite its good sensitivity well-established fabrication process, HEB suffers...