Yoshiichi Fukuda

Structure of Thin Layers of Some F. C. C. Metals Deposited on Oriented Ag, Pd and Ni Films

Some f. c. c. meas–Ni, Cu, Pd, Al, Au, Ag and Pb–were evaporated in vacuo on to oriented Ag, Pd and Ni films and the structure of the films was studied the transmission method of electron diffraction. Some films were composed of intermetallic compounds of deposit and substrate metals. But some films were composed of two layers of deposit and substrate metals. In the latter case, the deposit metals grew in the (001) or (111) oriented over growth on a substrate metal at a temperature higher than an epitaxial temperature. The occurrence of these two kinds of oriented overgrowth depended mainly on the percentage misfits.

Crossover behavior of systems associated with extended-defect N-component systems in cubic anisotropic crystals

Extended-defect N-component systems in cubic anisotropic crystals have fixed points of the Gaussian [G], Ising [PI], isotropic N-component [PN] and cubic anisotropic N-component [PcN] systems as regular (pure) systems, and those of the Ising [DI], isotropic N-component [DN], cubic anisotropic XY [DcXY] and cubic anisotropic N-component [DcN] systems as extended-defect systems. Crossover behavior near these typical fixed point systems is studied by means of a renormalization-group (RG) approach and characteristic curve (CC) method. Crossover exponents of the systems and their behavior are calculated and illustrated to linear order in ϵ (≡ − d; d = dimension of space) and ≈ϵ (≡ϵ + ϵd; ϵd = dimension of space occupied by extended defects (impurities)).

Vibration of Linear Lattice Containing Impurities

By using the scattering matrix, the effects of impurities on the vibration of linear lattice are studied. It can be shown that this treatment is equivalent to that using transfer matrix. In the present treatment, however, some simple formulas are obtained for the frequencies of localized modes.

Electronic States in Perturbed Two-Dimensional Graphite Lattice

By using a network model, the effects on the band structure of two-dimensional graphite due to localized perturbations are studied. The density of states near the Fermi energy is considerably modif...

On the critical dynamics of extended-impurity systems in cubic anisotropic crystals

Critical dynamics is studied for N-component spin systems in cubic anisotropic crystals in the presence of extended impurities, namely ed-dimensionally connected impurities distributed randomly in d∼ (≡ d − ed) dimensions (d: dimensionality of the medium; d ≡ 4 - e). As extended impurities make the systems coordinate-anisotropic, new results are expected in the critical dynamics. By means of a field-theoretic renormalization-group (RG) approach, critical regions and dynamic critical exponents are evaluated, to the lowest order in a double e, ed expansion, for models corresponding to model A, model B and model C, proposed by Hohenberg and Halperin.

Static and dynamic properties of XY systems with extended defects in cubic anisotropic crystallines

Static and dynamic critical behavior ofXY systems in cubic anisotropic crystallines, with extended defects (or quenched nonmagnetic impurities) strongly correlated alongɛd-dimensional space and randomly distributed ind − ɛd dimensions, were studied. These extended defects make the systems coordinate anisotropic, resulting in unique critical behavior due to competition between the cubic anisotropy and the coordinate anisotropy. The systems were analyzed by anɛ1/2 (ɛ≡4 − d) type of expansion with double expansion parameters based on a renormalization-group (RG) approach. Critical exponents were calculated near the second-order phase transition point and the behavior of the first-order transition was evaluated near the tricritical point.

Critical behavior of N-component spin systems with random impurities in cubic-anisotropy crystalline material

Static and dynamic critical behavior of N-component spin systems with cubic anisotropy and with quenched random impurities are studied in the limit ed→0+ of the impurity system whose impurities are strongly correlated in ed dimensions while they are randomly distributed in the remaining d − ed dimensions. By means of the renormalization-group approach, the stability of the fixed points, the flow of the interactions and the critical exponents are evaluated up to two-loop order. The behavior of the first order phase transition to appear is also studied.

Critical behaviour of two-component spin systems with quenched random nonmagnetic impurities in cubic anisotropic crystals

By means of the renormalisation-group approach, static and dynamic critical behaviours are studied for the XY spin system with cubic anisotropy and with quenched random nonmagnetic impurities. The stability of the quenched-random-impurity fixed point in d ( identical to 4- epsilon ) dimensions, the flow diagram of the interactions and the critical exponents are investigated, within the two-loop approximation, in terms of the epsilon 1/2 expansion. It is shown that the transition that appears is a first-order transition.

An Interpretation of the Oriented Overgrowth of Metal

Using a model of an oriented f.c.c. metal deposited on the (001) plane of some f.c.c. metal, the conditions under which the (001) or (111) oriented overgrowth takes place are studied theoretically in terms of the forces due to the deposit and substrate atoms. The forces are assumed to be of the Lennard-Jones type. The theoretical result is in a fairly good agreement with the experimental one.

Phase transition of binary-component DLA (diffusion-limited aggregation)-SQL (square lattice) system contacted with thermal bath in the perimeter

To make the DLA model associate with more realistic processes of crystal growth, the authors construct and study a new model including the experimental variables required. Diffusion particles of multicomponents diffuse on the square lattice as in the DLA model; the aggregation perimeter contacts with a thermal bath of temperature T and the sticking probability P consists of a constant probability Pc and the thermal one Pt at a neighbouring site of the perimeter, as P=(1- alpha )Pc+ alpha Pt ( alpha is a parameter which includes the non-equilibrium-equilibrium tendency of the system). Pt is evaluated by the thermodynamic distribution of the Ising system including up to next-nearest-neighbour interactions and chemical potentials. The system has the possibility of phase transitions. They show the phase transitions, aggregation patterns, correlation functions, fractal dimensions, and so on.