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Showing papers on "Spin-½ published in 1982"


Journal ArticleDOI
TL;DR: The solid-state cross polarization and magic-angle spinning analog of an earlier 2D FT experiment on liquids is introduced in this article, which permits the observation of spin exchange processes.

400 citations


Journal ArticleDOI
TL;DR: In this article, it was shown rigorously that the one-dimensional Ising model with long-range antiferromagnetic interactions exhibits a complete devil's staircase, which is the same as the one in this paper.
Abstract: It is shown rigorously that the one-dimensional Ising model with long-range antiferromagnetic interactions exhibits a complete devil's staircase.

330 citations


Journal ArticleDOI
TL;DR: Using the Bethe-Ansatz for a spin 1 2 Kondo model, the authors calculate the specific heat numerically, and use it to calculate the heat of a spin.

188 citations


Journal ArticleDOI
TL;DR: In this article, the dynamics of a dilute gas of free spin vortices in a two-dimensional planar magnet were investigated and an equation of motion for the spin vortex was presented and compared with the corresponding equation for a vortex in a superfluid film.
Abstract: We investigate the dynamics of a dilute gas of free spin vortices in a two-dimensional planar magnet. An equation of motion for the spin vortex is presented and compared with the corresponding equation for a vortex in a superfluid film. Exploiting a similar analogy with the dynamics of a two-dimensional plasma in a perpendicular magnetic field we calculate the mean-square vortex velocity and the vortex self-diffusion constant in the critical region above the phase transition. When combined with equations obtained previously for the spin-autocorrelation functions, our results provide an approximate description of the vortex contribution to the critical dynamics outside of the hydrodynamic regime.

188 citations



Journal ArticleDOI
TL;DR: The "constituent quark" substructure of ordinary hadrons is the consequence of small instanton radius ϱ c ⋍ 1 3 fm in the QCD vacuum.

176 citations


Journal ArticleDOI
TL;DR: In this article, a Peierls-dimerized chain was considered and the Gaussian field theory was applied to the case of polyacetylene, and it was shown that strong-coupling polarons in the dimerized chain can carry spin (12) and charge (±e).

161 citations


Journal ArticleDOI
TL;DR: In this article, the authors construct model field theories in which a confining gauge interaction binds massive elementary fermions into massless composite particles, where the massless composites are either Goldstone bosons or spin-1 2 fermians.

138 citations


Journal ArticleDOI
TL;DR: The spin transition in [Fe(2pic) 3 ]Cl 2 ·EtOH (2-pic = 2-picolylamine) has been reinvestigated by Mossbauer spectroscopy and magnetic susceptibility measurements as mentioned in this paper.

123 citations


Journal ArticleDOI
TL;DR: In this paper, a systematic calculation of high-spin potential-energy surfaces in the -γ-plane has been performed within the cranked Nilsson-Strutinsky model, and results from 407 even-even nuclei ranging from 6634Se to 21884Po are available, each at about ten different spin values.
Abstract: A systematic calculation of high-spin potential-energy surfaces in the -γ-plane has been performed within the cranked Nilsson-Strutinsky model. In all, results from 407 even-even nuclei ranging from 6634Se to 21884Po are available, each at about ten different spin values. In the case of I > 0 the pairing interaction is neglected, while it is accounted for at spin zero. Approximately 4200 different potential-energy surfaces are presented in the compact form of micro-fiche films.

106 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the two-point truncated correlation function decays exponentially (respectively with a power law) if the potential decays with respect to the power law.
Abstract: In unbounded spin systems at high temperature with two-body potential we prove, using the associated polymer model, that the two-point truncated correlation function decays exponentially (respectively with a power law) if the potential decays exponentially (respectively with a power law). We also give a new proof of the convergence of the Mayer series for the general polymer model.

Journal ArticleDOI
TL;DR: In this paper, a simple theory of spin diffusion is pressented and the response of the gas to a spin orientation gradient is calculated, taking into account the "identical spin rotation effect".
Abstract: The general results obtained in a preceding article (with the same title) are appliede to the study of transport phenomena in a spin polarized gas at low temperature, with particular emphasis on particle indistinguishability effects in collisions. A simple theory of spin diffusion is pressented and the response of the gas to a spin orientation gradient is calculated, taking into account the "identical spin rotation effect". The hydrodynamic equations of evolution of the spin orientation give rise to oscillations (spin waves). .....

Journal ArticleDOI
TL;DR: In this article, a generalized RPA approach was proposed to account for the Mott transition, and some preliminary very rough numerical estimates were given for the low-density limit of the spin degrees of freedom.
Abstract: We first generalize the approach of the previous paper by including spin degrees of freedom. We classify the various spin states and we discuss the effect of interband exchange interactions. We then introduce screening, in the framework of a generalized RPA which incorporates Bose condensation of bound electron-hole pairs. We discuss in detail the low density limit : screening corrections do not change the sign of the compressibility, which remains positive, in contrast to previous estimates. We show that such RPA corrections reduce to an approximate form of the Van der Waals attraction between excitons. Viewing this RPA approach as an interpolation procedure at intermediate densities, we propose several interpolation schemes that should account for the Mott transition, and we give some preliminary very rough numerical estimates. Finally, we discuss the effect of band degeneracy on the ground state : different degeneracies in the two bands should lead to a normal plasma at high density while at low densities bound excitons « Bose condense », with a breakdown of their internal symmetry; we expect a first order transition with a liquid-gas phase separation.

Journal ArticleDOI
TL;DR: In this paper, an explanation for the observed inverse quadratic dependence of the spectral spin-diffusion rate constant on the frequency difference of the two involved spin species in the presence of a large extraneous dipolar reservoir is presented.
Abstract: An explanation is presented for the observed inverse quadratic dependence of the spectral spin-diffusion rate constant on the frequency difference of the two involved spin species in the presence of a large extraneous dipolar reservoir. The result applies to spin diffusion in the laboratory frame and to cross polarization in a rotating frame.

Journal ArticleDOI
TL;DR: In this article, a renormalization scheme based on a natural choice of input parameters, i.e. electron charge e and the masses of all particles (Mw, Mz, Mx and fermion masses mf) is considered.

Journal ArticleDOI
TL;DR: In this paper, noncanonical Poisson brackets for four theories of superfluid theory are presented: irrotational 4 He, rotating 4 He and anisotropic liquid 3 He-A without spin.


Journal ArticleDOI
01 Nov 1982
TL;DR: In this paper, a spin-adapted linear response theory in a coupled-cluster framework was proposed to calculate the spin-allowed and spin-forbidden transition energies from a single methodology.
Abstract: In this paper, we have spin-adapted our recently formulated linear response theory in a coupled-cluster framework. This allows us to calculate directly both the spin-allowed and the spin-forbidden transition energies from a single methodology. We have introduced rank-zero and rank-one spin operators to construct excitation operators for singlet-singlet and singlet-triplet transitions respectively and utilised the graphical methods of spin algebra to integrate the spin variables. It has been shown how a suitable parameterisation of the reduced Hugenholtz matrix elements of the excitation operator in terms of Goldstone matrix elements makes the resulting system of equations simple, compact and suitable for computer implementation. A pilot calculation has been performed to test the applicability of the theory.


Journal ArticleDOI
Tôru Moriya1
TL;DR: In this article, the magnetic properties of typical ferromagnetic metals are discussed on the basis of the previously developed unified theory with the use of relatively small number of physical parameters including the longitudinal and transverse (exchange) stiffness constants for the spin fluctuation.
Abstract: Magnetic properties of typical ferromagnetic metals are discussed on the basis of the previously-developed unified theory with the use of relatively small number of physical parameters including the longitudinal and transverse (exchange) stiffness constants for the spin fluctuation From the analysis of existing experimental results we discuss on the temperature variation of the amplitude of local spin fluctuation (local moment) and the degree of short rang order in Pd 2 MnSn, Fe 3 Pt, CoS 2 , Fe, Co, Ni and MnSi

Journal ArticleDOI
TL;DR: In this paper, the properties of magnetic sources carrying electric charge are investigated, with emphasis on the meaning of angular momentum for these systems, and the nature of phases which affect the statistics of indistinguishable objects.
Abstract: Delicacies in quantum physics for magnetic sources carrying electric charge, recently exposed by Wilczek, are studied further, with emphasis on the meaning of angular momentum for these systems, and the nature of phases which affect the statistics of indistinguishable objects. Wilczek has uncovered a remarkable two-body interaction which leads to a many-body system in two dimensions changing from Bose gas to Fermi gas as the interaction parameter is varied. A nontrivial realization of these notions might occur in a thin sheet of superconductor with many magnetic vortices.

Journal ArticleDOI
TL;DR: In this paper, the Woods-Saxon potential is employed to interpret the properties of single particle and high spin spectra of a single particle, and spin-orbit potential parameters are found which simultaneously reproduce the experimental yrast and yrare states up to $I\ensuremath{\sim}18$ and generate the proton single particle energy gap = 2.0$ MeV.
Abstract: The Woods-Saxon potential is employed to interpret the properties of single particle and high spin spectra of $^{146}\mathrm{Gd}$. Spin orbit potential parameters are found which simultaneously reproduce the experimental yrast and yrare states up to $I\ensuremath{\sim}18$ and generate the proton single particle energy gap ${\ensuremath{\delta}}_{p}=2.0$ MeV. The spin-orbit potential parameters obtained are nearly identical for neutrons and protons and are close to the parameter values obtained previously by optimizing the potential to high spin spectra in the vicinity of $^{208}\mathrm{Pb}$. Properties of the pairing correction method, the Bardeen-Cooper-Schrieffer approximation with blocking, and the particle number projection are discussed and illustrated. It is demonstrated that including the particle number projection term in the total energy formula improves considerably the average slope of the calculated yrast line. The possibility of the collective quadrupole vibrational states becoming yrast states is studied for $I\ensuremath{\gtrsim}7\ensuremath{\hbar}$ using the random phase approximation but only a rather weak effect of collectivity is found in the spin-range studied.NUCLEAR STRUCTURE $^{146}\mathrm{Gd}$; Woods-Saxon single-particle levels, high spin excitations. Collectivity in the high spin states, RPA.





Journal ArticleDOI
TL;DR: In this paper, the functional derivative of the Weizsacker kinetic energy of a noninteracting system of particles with density ρ =ρ↑+ρ↓ is evaluated in terms of the Kohn-Sham spin orbital densities ρiσ and Lagrange multipliers eiσ(σ=↑ or ↓).
Abstract: The functional derivative of the kinetic energy Ts[ρ↑,ρ↓] of a noninteracting system of particles with density ρ=ρ↑+ρ↓ is evaluated in terms of the Kohn–Sham spin orbital densities ρiσ and Lagrange multipliers eiσ(σ=↑ or ↓). Of particular interest is the functional derivative of TΔ[ρ↑,ρ↓] =Ts[ρ↑,ρ↓]−Tw[ρ↑,ρ↓], where Tw[ρ↑,ρ↓] is the Weizsacker kinetic energy functional: δTΔ[ρ↑,ρ↓]/δρσ =(1/8ρσ){JNσi=1[(∇ρiσ ⋅ ∇ρiσ)/ρiσ −(∇ρσ ⋅ ∇ρσ)/ρσ]} −(1/ρσ)(JNσi=1 eiσρiσ −μσρσ). This quantity is used to analyze the approximate kinetic energy density functional proposed by Acharya et al.


Journal ArticleDOI
TL;DR: An exact vacuum solution of the field equations describing two isolated bodies balanced by their gravitational spin-spin interaction is presented in this paper, which is based on the same model as ours.
Abstract: An exact vacuum solution of Einstein's field equations describing two isolated bodies balanced by their gravitational spin-spin interaction is presented.

Journal ArticleDOI
TL;DR: In this paper, an equation of motion for a spin vortex in a two-dimensional easy plane magnet is presented and discussed, based on earlier work on the dynamics of magnetic domains and including the effects of vortex-vortex interactions, (weak) applied fields, and dissipation.
Abstract: An equation of motion for a spin vortex in a two‐dimensional easy plane magnet is presented and discussed. The theory is based on earlier work on the dynamics of magnetic domains and includes the effects of vortex‐vortex interactions, (weak) applied fields, and dissipation. A possible approach to detecting vortices is also discussed.