High temperature series expansion for the spin 12XY-model in a magnetic field

Series expansions for the partition function and the fluctuation in the long range order parameter are presented for the spin $\text{1}\text{2}$XY-model on the f.c.c. lattice with an external magnetic field in the z-direction.     

Exactly solvable spin-12 quantum chains with multispin interactions

A generalized spin-$\text{1}\text{2}$ quantum chain with m (n) spin interactions for the z (x) component of the spins is shown to be self-dual. Through duality, the m arbitrary, n = 2 version of the model is transformed into m independent Ising chains in a transverse field, allowing us to get the exact values of the critical exponents for any m (v = s = z = 1; β = m/8; n_x = m/4) and the spectrum. The anisotropic XY chain is a particular case with = 2.     

Ising lattices with four-spin interactions

A derivation is given of the magnetic ground states for the spin-$\text{1}\text{2}$ Ising model with pure four spin interaction on cubic lattices with infinite order parameter dimensionality. The results depend on the periodic boundary conditions that must be used in infinite systems. A new type of boundary condition is thus suggested which enables us to calculate the order parameter dimensionality, with no further assumptions. This system is simpler and gives lower values than those found previously.     

Generating functional approach to the Green's functions diagrammatic technique for spin and pseudospin lattice systems: I. General theory

The theory of the irreducible many-point Green's functions, describing spin and pseudospin lattice systems, is formulated with the help of the generating functional approach. The diagrammatic technique for the generating functional is also developed. Special attention is paid to the construction and summation of the diagrammatic series for the one- and two-point Green's functions. Closed formulae for the one-point Green's function and the generalized Vaks-Larkin- Pikin equation are obtained. The $\text{1}\text{z}$ expansion scheme near the critical temperature of the order-disorder phase transition, is discussed, where z denotes the effective number of nearest- neighbours for a given site in a crystal lattice.     

NMR relaxation at low temperature in one dimensional antiferromagnets: Comparison between S = 12 and S = 52

The proton spin-lattice relaxation time T₁ has been measured at low temperatures in spin $\text{5}\text{2}$ (CH₃)₄NMnCl₃ (TMMC) and spin $\text{1}\text{2}$ CuCl₂2NC₅H₅ (CuPC). The two systems have very different temperature dependences which we attribute to the different spin values.     

Quantum renormalizations in one dimensional easy plane ferromagnets

We examine the quantum corrections to the spin wave energies of easy plane ferromagnets. We utilize a formalism developed by Villain, and we obtain the quantum corrections of orders $\text{S(S + 1)}{}^{\mathrm{<mtext>-1</mtext><mtext>2</mtext>}}$. The experimentally determined spin wave spectra for CsNiF₃ is used to find the bare exchange J and anisotropy parameter D. We compare our values with those obtained from other theories, which order the corrections in powers of S^-1 and also neglect higher powers of D/J.     

1f noise in spin glasses and in the disordered kinetic ising model

In systems in which the relaxation towards equilibrium follows a logarithmic law (e.g. in spin glasses) the spectrum of the noise in the thermodynamic equilibrium state is proportional to $\text{1}\text{f}$ in an extremely wide frequency range. The disordered kinetic Ising model in which the absolute values and signs of interaction energies are random is a model of a physical system exhibiting $\text{1}\text{f}$ noise.     

Intrinsic and rotational states in 173Ta

High spin rotational levels in ¹⁷³Ta are populated in the ¹⁶⁵Ho(¹²C, 4n)¹⁷³Ta and ¹⁷⁵Lu(α, 6n)¹⁷³Ta reactions. The de-excitation γ-ray cascades are studied with Ge(Li) detectors. The rotational bands, which are built on the $\text{7}\text{2}$⁺(404), $\text{5}\text{2}$⁺(402), $\text{9}\text{2}$^?(514) and $\text{1}\text{2}$^?(541) intrinsic states, are identified up to high spin values. A state, interpreted as a three quasi-particle state with a probable spin of $\text{21}\text{2}$ is located at 1713 keV. Its half-life is about 100 ns. The behaviour of the moment of inertia of each rotational band versus the rotational frequency is compared with that of the doubly even core.     

Extreme values of the spin polarization analyzing power in nuclear reactions

States of maximum possible polarization are investigated for ensembles of spin-$\text{1}\text{2}$ and spin-1 particles in nuclear reactions. General criteria for extreme values of some components of the analyzing power are given and applied to the formulae for the observables of reactions with various spin spaces. Experimental data relevant to possible extreme values are discussed.     

Polarization transfer in deuteron stripping reactions

Polarization phenomena involving the spins of a and b in the A(a, b)B reaction are discussed using a complete set of irreducible tensors carrying definite spin transfer. The linear model independent equations relating the cross section and the polarization observables with these tensors are shown to be particularly appropriate for the study of spin dependent interactions, preferentially associated with particular values of spin transfer. The DWBA theory of polarization transfer in deuteron stripping reactions is thoroughly discussed and among the 17 polarization observables we distinguish those likely to be more sensitive to spin dependent distortion, to have stronger deuteron D-state effects, to exhibit the sign-rule j-dependence and other forms of j-dependence. For certain deuteron polarizations, when the spin transfer is pure $\text{s =}\text{1}\text{2}$, it is shown that deuteron stripping reactions are transparent to vector polarization transfer and the outgoing nucléon polarization independent of scattering angle and deuteron energy. DWBA calculations including contributions from spin transfer $\text{3}\text{2}$ through the deuteron D-state and spin-orbit distortion show that polarization transfer in such deuteron polarizations can be explored as a method of producing fast polarized neutrons with known polarization.     

Dynamics of the infinite-range ising spin glass

The Glauber dynamics of an Ising spin glass with infinite-range interactions and additional static field, h, is investigated near the freezing temperature, T_f. We obtain critical slowing down at and below the de Almeida-Thouless instability line, h_c(T), to order (1?T/T_f)³ with algebraic decay of the spin correlations ～t^?ν, where $\text{ν=}\text{1}\text{2}$ at T_f and $\text{ν≤}\text{1}\text{2}$ for T<T_f.     

A puzzling combination: Disorder × order

There are several examples indicating that the operator combination “disorder × order” creates anomalous spin and/or statistics. In 2 + 1 dimensions there is a similar anomaly related to the disorder operator carrying Z(N) topological charge believed to have an important role in quark confinement. The conventionally defined total angular momentum has an anomalous term $\text{1}\text{2}\text{σ}{}^3\text{((}\text{1}\text{√3}\text{)λ}{}^8\text{)}$ and can take the values $\text{1}\text{2}\text{(}\text{1}\text{3}\text{)}$ in the presence of “disorder × order” in 2 + 1 dimensional SU(2) (SU(#)) gauge theories. It is argued that the existence of a stable soliton solution or the introduction of Higgs fields are not important for the anomaly.     

Calculation of a pair correlation function for the three-dimensional Ising model with long-range exchange forces

A simple difference equation for one type of correlators has been obtained by the method of direct calculation of the correlation functions (CF). It is correct for the Ising model of an arbitrary dimension with the exactness $\text{O}$($\text{1}\text{z}$) (z-number of particles covered by the interaction potential). The equation obtained is used to calculate the pair CF 〈S^z_fS^z_j〉 in the three-dimensional Ising model with long-range forces which are of importance when dealing with the applied magnetic problems. The results of the calculations lead to corrections in the Ornstein-Zernike (OZ) theory.     

On a possible test of massive high spin wave equations in heavy-ion scattering

Cross sections and polarization functions for elastic scattering of identical particles with spin 1 are compared in the relativistic $\text{(s,0)+(s?}\text{1}\text{2}\text{,}\text{1}\text{2}\text{)}$ invariant theory, for arbitrary spin, and the $\text{(}\text{1}\text{2}\text{,}\text{1}\text{2}\text{)}$ invariant Proca theory. Heavy-ion scattering is suggested to test high spin theories.     

Usefulness of spin dependent electromagnetic hadronic inteference experiments

For the collision of a beam of neutral spin $\text{1}\text{2}$ particles A with a polarized target of spin $\text{1}\text{2}$charged particles B, it is shown that many spin dependent observables display a simple and characteristic structure in t which can be utilized to measure directly the magnitude and phase of the hadronic amplitudes, both helicity-flip and non flip, in the forward direction.     

X-ray photoelectron spectra of iron complexes: Correlation of iron 2p satellite intensity with complex spin state

Metal and ligand core-level spectra have been obtained for 36 iron complexes which possess a variety of ligands including carbonyl, nitrosyl, triphenylphosphine,o-phenylenebis(dimethylarsine), halides and pseudohalides. Formal metal oxidation states range from ? 1 to + 3, and complex spin states represented in the series include 0, $\text{1}\text{2}$, $\text{3}\text{2}$, 2 and $\text{5}\text{2}$. A clear correlation between complex spin state and satellite intensity in the Fe 2p spectra is found. The satellite intensities observed experimentally are in approximate quantitative accord with those predicted by a “spin flipping” model. Although the present analysis does not provide a definitive choice between the “sudden approximation” and “spin flipping” models, the agreement between experimental satellite intensities and the intensities predicted by the “spin flipping” model suggests that such a mechanism can be important in the satellite process.     

The magnetic dipole moment of 55Co

The ground state g-factor for ⁵⁵Co has been measured as $\text{¦g¦= 1.378±0.001}$ by the technique of nuclear magnetic resonance on oriented nuclei. The temperature dependence of γ-ray anisotropy in the ⁵⁵Fe daughter decay determines both the 1408 keV level spin and the ⁵⁵Co ground state spin to be $\text{7}\text{2}$, and yields values of mixing ratios in the 1037 keV β-transition and the 477 keV γ-transition. The configuration mixing model is used to discuss 1f_{$\text{7}\text{2}$} moment systematics.     

On the definition of the pressure of an infinite system

A microcanonical system $\text{L}$^o_Λ is considered together with a manometer $\text{M}$_Λ. The thermodynamic limit Λ → ∞ is taken for the system $\text{L}$_Λ composed of $\text{L}$^o_Λ and $\text{M}$_Λ. This yields a definition of the pressure P(v, ε) of $\text{{}\text{L}{}^{\mathrm{o}}{}_{\mathrm{\Lambda }}\text{; Λ → ∞}}$ for given values ε and v of the energy and particle densities. P(v, ε) is shown to be equal to the thermodynamic function p(z, β) derived from the grand canonical ensemble for almost all values of ε and v provided the appropriate equilibrium values of the temperature β^?1 and the chemical potential μ = β^?1 log z are inserted.     

The de Haas-van Alphen effect in Kondo systems

In Kondo systems, de Haas-van Alphen experiments determine a spin-splitting term in the conduction-electron self-energy. It is shown that for all temperatures and magnetic fields, and in the presence of normal potential scattering, spin-splitting of Landau levels is given exactly with:

$\text{Re Σ↓(0) - Re Σ↑(0) = cJ〈S}{}_{\mathrm{z}}\text{〉}{}_{\mathrm{K}}$

Σ(0) is the conduction-electron self-energy at the Fermi level and 〈S_z〉_K is the expectation value for the impurity spin including Kondo effects.     

Spin and lifetime of the ω− hyperon

A total of 101 ω^? decays have been found in K^?p interactions at 10 and $\text{16 GeV}\text{c}$. The decay angular distribution has been fitted under the assumptions that the ω^? has spin either $\text{1}\text{2}\text{or}\text{3}\text{2}$. It has been found that the probability of isotropy (spin$\text{1}\text{2}\text{)}$ is less than one in a thousand, whereas the probability for spin $\text{3}\text{2}$ is about 70%. Thus, we exclude the spin $\text{1}\text{2}$ assignment. The lifetime of the ω^? is found to be (1.41_?0.24^+0.15) × 10^?10s, in agreement with our earlier result based on about $\text{1}\text{5}$ of the present sample.