Materials Literature
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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…
We present a theory for the calculation of the self-consistent-field dynamical polarizability and hyperpolarizabilities of molecular solutes described within the framework of the polarization continuum model. The formulation is characterized by the use of a cavity accurately modeled on the molecular shape of the solva…
An efficient continuum model for simulating polymer blends and copolymers is presented. In this model, the interactions are short-range and purely repulsive, thus allowing for excellent computational performances. The driving force for phase separation is a difference in the repulsive interaction strength between like…
Recombination processes in rare-earth metals in semiconductors are a special case due to the localized nature of $f$ electrons. Our work explores in detail the radiative and nonradiative mechanisms of energy transfer for erbium in silicon by investigating the temperature dependence of the intensity and the decay time…
We study the processes of charge separation and transport in composite materials formed by mixing cadmium selenide or cadmium sulfide nanocrystals with the conjugated polymer poly(2-methoxy,5-(2\ensuremath{'}-ethyl)-hexyloxy-$p$-phenylenevinylene) (MEH-PPV). When the surface of the nanocrystals is treated so as to rem…
Finite graphite systems having a zigzag edge exhibit a special edge state. The corresponding energy bands are almost flat at the Fermi level and thereby give a sharp peak in the density of states. The charge density in the edge state is strongly localized on the zigzag edge sites. No such localized state appears in gr…
Acid-treated carbon nanotubes have been decorated with nanoscale Au, Pt and Ag clusters by employing several procedures. The nature and extent of metal coverage can be varied by changing the concentration of the metal compound or by mild sonication (treatment with ultrasound). The metal clusters seem to get deposited…
The transition metal chalcogenide Ni(S,Se)2 is one of the few highly correlated, Mott-Hubbard systems without a strong first-order structural distortion that normally cuts off the critical behavior at the metal-insulator transition. The zero-temperature (T) transition was tuned with pressure, and significant deviation…
Open carbon nanotubes were filled with molten silver nitrate by capillary forces. Only those tubes with inner diameters of 4 nanometers or more were filled, suggesting a capillarity size dependence as a result of the lowering of the nanotube-salt interface energy with increasing curvature of the nanotube walls. Nanotu…