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Momentum-resolved direct and inverse photoemission spectra of the $\mathrm{K}/\mathrm{Si}\left(111\right)\ensuremath{-}(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}\ensuremath{-}\mathrm{B}$ interface reveals the presence of strongly localized surface states. The K overlayer remains nonmetallic up to the saturation coverage. This system most likely presents the first experimental realization of a frustrated spin $1/2$ Heisenberg antiferromagnet on a two-dimensional triangular lattice.

High-temperature series for two bcc lattice models which interpolate between the Gaussian (or free-field) model and the $S=\frac{1}{2}$ Ising model are analyzed by partial differential approximants. Series to order 21 in both $x\ensuremath{\propto}\frac{1}{T}$ and the interpolation parameter, $y$, yield unbiased estimates for the correction-to-scaling exponent, $\ensuremath{\theta}=0.54\ifmmode\pm\else\textpm\fi{}5$, and the susceptibility exponent, $\ensuremath{\gamma}=1.2385\ifmmode\pm\else\textpm\fi{}15$. The results are universal and agree tolerably with field-theoretic estimates and well with biased, one-variable analyses of general spin Ising models.

Derives accurate compact expressions for the high-temperature specific heats of classical (S= infinity , 3-vector) spin systems on FCC, BCC and SC lattices for pure Heisenberg, XY and Ising-like couplings, respectively. The analysis of the appropriate series expansions demonstrates the utility of inhomogeneous differential approximants and supports the estimate alpha H=-0.21+or-0.04.

A new electrostatic method for the equilibrium properties of nonprimitive electrolyte solutions is proposed. The theory is developed in detail for a 1‐1 symmetric electrolyte composed of equal radius rigid spheres with embedded charges and dipoles. The theory is based on the following key ideas. The microscopic electrostatic equation for the ionic–polar mixture is reduced by averaging to a coupled hierarchy of effective electrostatic equations which depend, respectively, on the coordinates of 0, 1, 2, 3, etc., molecules. The first member of the hierarchy, which determines the macroscopic electrostatics in the solution, involves a salt concentration dependent dielectric constant e and a generalized Debye inverse screening length κ. These constitutive parameters are determined self‐consistently from the solutions of the second set of hierarchy equations. These are rendered tractable by a mean field closure of the hierarchy which is tantamount to assuming the constitutive parameters of the solution when one ...

Recent experiments on MnF2 (King and Rohrer, 1976, 1979) suggest Q=1.56+or-0.35 for the amplitude ratio determining how the critical lines meet at the spin-flop bicritical point, in serious disagreement with the original prediction of Q approximately=2.5>2.2 for universal Heisenberg (n=3) bicriticality. The authors report extensive two-variable series calculations using constrained partial differential approximants, which yield Q=2.34+or-0.08. In addition it is shown that the natural least-squares fitting procedures may be strongly biased even for data of high precision.

The critical properties of the model of a spin-glass proposed by Edwards and Anderson are studied using the renormalization group. The critical exponents are calculated in $6\ensuremath{-}\ensuremath{\epsilon}$ spatial dimensions. It is argued that a tricritical point can exist where the nonordering field is the skewness of the distribution of $J$.