Evolution of a rarefied two-dimensional Li phase with a concentration less than 1/50 of a monolayer has been found in the process of Li surface diffusion on Mo(112). The formation of this Li phase is interpreted as evidence of the existence of very long-range lateral interactions. We have also observed a nonmonotonic shape and quite unexpected development of Li concentration profiles on Mo(112).

The flat solid-fluid interface undergoes a roughening phase transition at the roughening temperature ${\mathit{T}}^{\mathit{r}}$. The step free energy λ vanishes at ${\mathit{T}}^{\mathit{r}}$, if the temperature T→${\mathit{T}}^{\mathit{r}}$. For n-paraffin crystals, the critical behavior of γ(T) in the neighborhood of ${\mathit{T}}^{\mathit{r}}$ is solvent dependent. If n-${\mathrm{C}}_{25}$${\mathrm{H}}_{52}$ crystals are grown from n-hexane solutions, the step free energy γ(T) of the {110} faces vanishes discontinuously at ${\mathit{T}}^{\mathit{r}}$. In contrast, for n-${\mathrm{C}}_{25}$${\mathrm{H}}_{52}$ crystals grown from toluene solutions γ(T) vanishes continuously at ${\mathit{T}}^{\mathit{r}}$, showing a Kosterlitz-Thouless type of roughening transition.

Alternating morphology transitions between dendrite and dense-branching morphology have been studied for the first time in electrochemical deposition of ${\mathrm{FeSO}}_4$ aqueous solution film. We suggest that the observed alternating transition is caused by the interchange of anisotropy in interfacial growth, which arises from the periodic accumulation and depletion of impurities in front of the growing interface in our experimental system. The selection problem in pattern formation is discussed.

In briefly annealed silicon samples implanted with hydrogen and deuterium an electron paramagnetic resonance spectrum is detected. It is identified as arising from a hydrogen molecule oriented in the 〈111〉 crystallographic direction and located most probably at an interstitial site. Such a result is consistent with recent theoretical calculations predicting such an orientation to be of lowest energy. In addition, evidence is obtained indicating that the hydrogen molecule forms a part of a more elaborate hydrogen cluster.

We investigate the properties of the Kuramoto-Sivashinsky equation in two spatial dimensions. We show by an explicit, numerical, coarse-graining procedure that its long-wavelength properties are described by a stochastic, partial differential equation of the Kardar-Parisi-Zhang type. From the computed parameters in our effective, stochastic equation we argue that the length and time scales over which the correlation functions cross over from linear diffusive to those of the full nonlinear equation are very large. The behavior of the three-dimensional equation is also discussed.

We have studied the electronic structure of the recently discovered superconducting body-centered-cubic alkaline-earth fullerides ${\mathrm{Sr}}_6$${\mathrm{C}}_{60}$ and ${\mathrm{Ba}}_6$${\mathrm{C}}_{60}$ using the local-density approximation in the density-functional theory. Both fullerides are found to be the novel semimetallic compounds of alkaline-earth atoms and ${\mathrm{C}}_{60}$ clusters in which the hybridization between the alkaline-earth-atom states and the ${\mathrm{C}}_{60}$ π states is essential for their metallic electronic structure, and consequently for the occurrence of the superconductivity.

We report on the electrical and magnetic properties of the layered ternary sulfide system ${\mathrm{BaCo}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Ni}}_{\mathit{x}}$${\mathrm{S}}_{2\mathrm{-}\mathit{y}}$. Ni doped samples of ${\mathrm{BaCoS}}_2$ that contain sulfur vacancies exhibit a first-order pahse transition from a high temprature antiferromagnetic, semiconducting phase to a low temperature metallic phase. Increasing the sulfur vacancy concentration increases the Néel temperature of the two-dimensional antiferromagnetic phase and decreases the resistivity in the metallic phase. As the Ni content is increased, the system undergoes a smooth transition to a paramagnetic metal at all temperatures.

We present self-consistent calculations for the self-energy, thermodynamic potential, and magnetic susceptibility of the 2D asymmetric Anderson lattice Hamiltonian, in the fluctuation exchange approximation. For parameters that yield a large local moment, a narrow peak at the Fermi energy grows out of an otherwise smooth density of states as the system is cooled. The height of the peak reaches a maximum and then decreases, signaling the onset of coherence. The susceptibility shows a similar temperature dependence.

Electron excitation energies and photoemission spectra in undoped, solid ${\mathrm{C}}_{60}$ are calculated using a quasiparticle approach. The effects of orientational disorder and electron correlations are studied. We find a band gap of 2.15 eV, in good agreement with experiment, and ∼1 eV widths for the highest-occupied-molecular-orbital (HOMO) and lowest-unoccupied-molecular-orbital (LUMO) bands. Calculated angle-resolved, inverse photoemission spectra for the LUMO bands show very little angular dependence, explaining recent experimental work on epitaxial thin films. The present results suggest that undoped, solid ${\mathrm{C}}_{60}$ is a standard band insulator.

For a periodically modulated electron channel, conductance quantization characteristic of a simple quantum point contact is recovered. The value of the quantized conductance is, however, no longer a monotonically increasing function of energy. Comparison with the band structure of the corresponding infinite channel shows a direct correspondence between the index of the conductance plateau and the number of positive-velocity bands at a given energy. The results persist in the presence of an applied magnetic field and lead to a prediction of nonmonotonic steps in the integer quantum Hall resistance for such structures.

We predict the Shubnikov–de Haas oscillations of the fine structure of the cyclotron resonance near its crossing with the spin resonance in the degenerate two-dimensional Coulomb gas subjected to a strong tilted magnetic field. The spin-orbit coupling splits these resonances into three lines with the splitting gaps varying with the filling factor from ${\mathit{v}}_{\mathrm{so}}$${\mathit{p}}_{\mathit{F}}$ to ${\mathit{v}}_{\mathrm{so}}$${\mathit{p}}_{\mathit{F}}$/ √2 at odd- and even-integer filling, respectively. This indicates re-entrance of the system into a partially spin-polarized state and can be treated as manifestation of a new spin-density wave mode in it.

The time-dependent density functional approach is used to calculate the wave-vector dispersion of the surface plasmon of Ag. The 5s conduction electrons are treated as a semi-infinite homogeneous electron gas and the influence of the 4d electrons is described in terms of a polarizable medium. It is shown that the reduction of the s-d screening interaction in the surface region leads to a positive dispersion of the surface plasmon in agreement with recent electron energy loss measurements.

Ballistic-electron-emission microscopy (BEEM) of Au and Mg films on n-type GaP(110), with thicknesses as low at 12 Å, reveals strong variations of spectral shape and magnitude of the BEEM current with metal-film thickness and surface gradient. Using Monte Carlo simulations, the hot-electron transport between tip and semiconductor can be quantitatively described, providing detailed information on tunneling, transport in the metal, transmission across the interface, and impact ionization in the semiconductor.

This work provides a theory of the general structure of mixed-spin fractional quantum Hall states, which are relevant at low magnetic fields. This, in particular, leads to a microscopic description of the experimetnally observed mixed-spin states at ν=2/3, 4) / 3 , and 3/5. Antiparallel-flux-attachement transformation of the composite fermion theory plays an important role in explaining the mixed-spin states in the filling factor range 3/2>ν>1/2.

Measurements of the zero-field resistive transition of ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$${\mathrm{CaCu}}_2$${\mathrm{O}}_8$ single crystals suggest that a bulk zero-resistance state develops through a sequential process characterized by two transition temperatures. The upper transition corresponds to Josephson coupling of parallel CuO bilayers, and the lower transition to the conventional Kosterlitz-Thouless dissociation of bound vortex excitations. Measurements using a ‘‘flux transformer’’ electrode geometry indicate a pronounced peak in the secondary voltage, which is suppressed by an external magnetic field.

Although the master equation describing long-range random walks on an energetically disordered lattice is governed by a nonsymmetric transition matrix W, it may be mapped through a similarity transform onto an imaginary-time Schrödinger equation governed by a Hermitian (Hamiltonian) operator ${\mathit{H}}_0$ having a nondegenerate ground state. Under this mapping the diffusion constant D can be expressed in terms of the exact ground state energy of operators that are infinitesimally perturbed from ${\mathit{H}}_0$.

Interlayer vortex decoupling is directly observed as a function of temperature and applied magnetic field via electronic transport perpendicular to the layers in a synthetic model system consisting of MoGe/Ge multilayers. Below the decoupling temperature ${\mathit{T}}_{\mathit{D}}$ the resistivity anisotropy collapses and striking nonlinearities appear in the perpendicular current-voltage behavior, which are not observed in parallel transport. A crossover in behavior is also observed at a field ${\mathit{H}}_{\mathit{x}}$, in accordance with theory.

The cluster-variation method is used to study the phase diagram of the Blume-Emery-Griffiths model on a simple cubic lattice. The main attention is paid to the ferrimagnetic phases occurring in a certain range of coupling parameters. A new topology, including three ferrimagnetic phases, is obtained in the vicinity of the line in parameter space where the model reduces to the antiferromagnetic three-state Potts model. The results imply the existence of three phase transitions in the antiferromagnetic Potts model.

We present the theory of two-dimensional, clean quantum antiferromagnets with a small, positive, zero temperature (T) stiffness ${\mathrm{\rho }}_5$, but with the ratio ${\mathit{k}}_{\mathit{B}}$T/${\mathrm{\rho }}_{\mathit{s}}$ arbitrary. Universal scaling forms for the uniform susceptibility (${\mathrm{\chi }}_{\mathit{u}}$), correlation length (ξ), and NMR relaxation rate (1/${\mathit{T}}_1$) are proposed and computed in a 1/N expansion and by Monte Carlo simulations. For large ${\mathit{k}}_{\mathit{B}}$T/${\mathrm{\rho }}_{\mathit{s}}$, ${\mathrm{\chi }}_{\mathit{u}}$(T)/T and Tξ(T) asymptote to universal values, while 1/${\mathit{T}}_1$(T) is nearly T independent. We find good quantitative agreement with experiments and some numerical studies on ${\mathrm{La}}_{2\mathrm{-}\mathrm{\delta }}$${\mathrm{Sr}}_{\mathrm{\delta }}$${\mathrm{CuO}}_4$.

We study the nonequilibrium relaxation of the spherical spin-glass model with p-spin interactions in the N→∞ limit. We analytically solve the asymptotics of the magnetization and the correlation and response functions for long but finite times. Even in the thermodynamic limit the system exhibits ‘‘weak’’ (as well as ‘‘true’’) ergodicity breaking and aging effects. We determine a functional Parisi-like order parameter ${\mathit{P}}_{\mathit{d}}$(q) which plays a similar role for the dynamics to that played by the usual function for the statics.