We present a set of exactly solvable fermionic spin-S Ising model on a square-type lattice including a quartic interaction term in the Hamiltonian, using an auxiliary mixed fermionic spin-(S,1/2) square-type lattice with only first nearest-neighbor interaction. The particular properties of the mixed lattice, associated to the fermionic mixed spin-(S,1/2), allow us to map this system either into...

We describe a simple approach for calculating the effective conductivity, dielectric constant, and magnetoresistance of periodic composites, by reducing the composite to an effective impedance network. The method is used to calculate the effective conductance of periodic two-dimensional binary composites on a square lattice, in good agreement with previous calculations using other methods. We u...

Neutron diffraction on the double perovskite Sr(2)YRuO(6) with a quasi-fcc lattice of Ru moments reveals planar magnetic correlations that condense into a partial long-range ordered state with coupled alternate antiferromagnetic (AFM) YRuO(4) square layers coexisting with the short-range correlations below T(N1) = 32 K. A second transition to a fully ordered AFM state below T(N2) = 24 K is obse...

(1) Exact universal amplitude ratios for two-dimensional Ising model and a quantum spin chain. (2) Critical behaviour of semi-infinite quenched dilute Ising-like systems in three dimensions: Ordinary transition. (3) Universal scaling functions for bond percolation on planar random and square lattices with multiple percolating clusters. (4) Polydispersity effect and universality of finite-size s...

NMR, μSR, magnetization and specific heat measurements in Li2VOSiO4 powders and single crystals are reported. Specific heat and magnetization measurements evidence that Li2VOSiO4 is a frustrated two-dimensional S = 1/2 Heisenberg antiferromagnet on a square lattice with a superexchange coupling J1, along the sides of the square, almost equal to J2, the one along the diagonal (J2/J1 = 1.1 ± 0.1 ...

We report the realization and characterization of a tunable, two-dimensional Talbot array illuminator for mid-infrared (MIR) wavelengths. A phase array, prepared by deposing tindoped indium oxide electrodes on a square-lattice-geometry poled LiNbO3 sample, is

The theory of magnetic symmetry in quasicrystals, described in a companion paper [Lifshitz & Even-Dar Mandel (2004). Acta Cryst. A60, 167-178], is used to enumerate all three-dimensional octagonal spin point groups and spin-space-group types and calculate the resulting selection rules for neutron diffraction experiments.

– We present Monte Carlo simulation results on the equilibrium relaxation of the two dimensional lattice Coulomb gas with fractional charges, which exhibits a close analogy to the primary relaxation of fragile supercooled liquids. Single particle and collective relaxation dynamics show that the Stokes-Einstein relation is violated at low temperatures, which can be characterized by a fractional ...