Materials Literature
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Photoluminescence decay times and quantum yields were measured at 77 K in the spectra of two Si-doped diamond films grown by the chemical-vapor deposition technique. A decay time of 950 ps for both films and a quantum yield of 0.05 for one film were determined for the Si center zero-phonon optical transition at 737 nm…
Electrical resistivity ($\ensuremath{\rho}$) and Seebeck-coefficient measurements ($\ensuremath{\alpha}$) are reported for $\mathrm{Ni}{\mathrm{S}}_{2\ensuremath{-}x}{\mathrm{Se}}_{x}$ single crystals in the range $0<~x<~0.71$. There is a general trend toward increasing metallicity with increasing $x$. In the ra…
We study the nonradiative Auger decay of excitons in ${\mathrm{Cu}}_{2}$O, in which two excitons scatter to an excited electron and hole. The exciton decay rate for the direct and the phonon-assisted processes is calculated from first principles; incorporating the band structure of the material leads to a relatively s…
The first spectroscopic characterization of the VO2 radical is reported along with new results for V17O and tentative assignments for the VO3 and V+2 radicals. These vanadium radicals were investigated in neon matrices at 4 K by electron spin resonance utilizing conventional high temperature vaporization and pulsed la…
The infrared local mode at 1450 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ in diamond, called H1a, has been studied in samples containing mixtures of $^{12}\mathrm{C}$ and $^{13}\mathrm{C}$ in several different ratios. It was previously associated with a nitrogen interstitial, assumed to be on a 〈001〉 split site [G. S…
We explore the application of the semiconducting phases of YBaCuO thin films as a bolometer for uncooled infrared detection. For this study, four different structures were built with different types of buffer layers: YBaCuO on a Si substrate with and without a MgO buffer layer, and on an oxidized Si substrate with and…
The spatial distributions of the cathodoluminescence (CL) emissions from thin ZnS films on GaAs(100) have been examined by the low-temperature CL measurement system combined with a transmission electron microscope (TEM). The correlation between these CL emissions and structural defects were studied by comparing the mo…
The atomic structure of the 2\ifmmode\times\else\texttimes\fi{}4 reconstructed GaAs (001) surface, prepared in optimized molecular beam epitaxy growth conditions, has been fully determined by in situ grazing incidence x-ray diffraction measurements. The structure involves only two dimers in the As top layer, in agreem…
We have proposed ReMnO3 (Re: rare earth) thin films for nonvolatile memory devices. We examine the growth mechanism of YMnO3 films on (0001)ZnO:Al/(0001) sapphire substrate using rf magnetron sputtering and pulsed laser deposition methods with oxide compound target. We have succeeded in obtaining (0001) epitaxial YMnO…
We have studied photoluminescence (PL) properties of surface-oxidized Ge nanocrystals with a 3.7 nm diameter. A difference between the absorption and PL excitation spectra and time-resolved PL measurements show that the site for the radiative recombination of excitons is different from that for the photogeneration of…
Neutron-scattering experiments have been performed on a LaMnO 3 single crystal. The spin waves exhibit two-dimensional anisotropic dispersion, that is, strong planar ferromagnetic coupling and weak antiferromagnetic interplane coupling with a finite gap. The critical exponent β of the order parameter is 0.25 ±0.01, wh…
Spin-resolved and high-energy-resolution x-ray-photoelectron spectra of the 3d, 4d, 4f, and 5p levels of ferromagnetic Gd are reported. The experimental spectra are compared with theoretical predictions for bulk Gd based on atomic multiplet calculations. The agreement is quite good when the Slater integrals are reduce…
Single crystals of PdCoO 2 have been successfully grown using the metathetical reaction. The obtained crystals have silverly metallic lustre and a well-habited hexagonal platelet shape. Anisotropic temperature dependence of the electrical resistivity and magnetic susceptibility have been first clarified. The resistivi…
Metal-insulator transitions of La 3 Ni 2 O 7-δ and La 4 Ni 3 O 10-δ with layered structure have been studied. Transport and magnetic measurements up to 1000 K have revealed an existence of the sharp transition in both systems at 550 K from a metallic but less conducting state with localized spins at Ni sites to the Pa…
The real dielectric constant of gallium arsenide has been determined at 300 and at 5 K from fits to observed interference in transmission of thin samples with parallel surfaces. Measurement was carried out over all or part of the range 30–4000 cm−1. An accuracy of ±0.5% is estimated based on the quality of the analyti…
The single particle dynamics of a 2D liquid made up of soft disks interacting by a repulsive r−12 potential are studied using molecular dynamics simulations. We find that mean squared particle displacement 〈Δr(t)2〉 behaves diffusively, i.e., increases linearly with time, within a time interval tc very much shorter tha…
X-ray-diffraction observations of strains induced by vapor adsorption are reported for porous silicon single-crystal samples. Two types of porous silicon ($p$ and ${p}^{+}$) with very different pore structure are investigated. A low-pressure contraction is observed in $p$-type samples with spherical pores of about 3-n…
By use of femtosecond differential absorption spectroscopy the electron-hole pair relaxation times have been determined in CdSe quantum dots with excited state energies larger than the LO-phonon energy. The fast energy relaxation within 500 fs is independent of the relation between level spacing and LO-phonon energy a…
In this work we present a study of the magnetic and transport properties of the system ${\mathrm{LaNiO}}_{3\mathrm{\ensuremath{-}}\mathit{x}}$ (0\ensuremath{\leqslant}x\ensuremath{\leqslant}0.5) where the x=0 member is a well-known metallic oxide. We found that the x=0.5 compound is an antiferromagnetic insulator at r…
In order to study the electrical transport of holes in LaCo${\mathrm{O}}_{3}$, the bulk conductivities and dielectric properties in a polycrystalline specimen were investigated. The bulk conduction was separated from others by complex-plane impedance analysis. At high temperatures, i.e., $T>170$ K, the activation e…