Showing papers on "Spin-½ published in 1980"
TL;DR: The authors assess various approximate forms for the correlation energy per particle of the spin-polarized homogeneous electron gas that have frequently been used in applications of the local spin density a...
Abstract: We assess various approximate forms for the correlation energy per particle of the spin-polarized homogeneous electron gas that have frequently been used in applications of the local spin density a...
17,531 citations
TL;DR: A theoretical analysis of the excitation spectrum of long-chain polyenes is presented in this paper, where one electronic state is localized at the gap center for each soliton or antisoliton present and the soliton's energy of formation, length, mass, activation energy for motion, and electronic properties are calculated.
Abstract: A theoretical analysis of the excitation spectrum of long-chain polyenes is presented. Because of the twofold degeneracy of the ground state of the dimerized chain, elementary excitations corresponding to topological solitons are obtained. The solitons can have three charge states $Q=0$. $\ifmmode\pm\else\textpm\fi{}e$. The neutral soliton has spin one-half while the charged solitons have spin zero. One electronic state is localized at the gap center for each soliton or antisoliton present. The soliton's energy of formation, length, mass, activation energy for motion, and electronic properties are calculated. These results are compared with experiment.
2,276 citations
TL;DR: In this article, it was shown that in all theories with a Lorentz-covariant energy-momentum tensor, such as all known renormalizable quantum field theories, composite as well as elementary massless particles with j > 1 are forbidden.
562 citations
TL;DR: A massive Dirac neutrino has a magnetic moment which causes its spin to precess in a magnetic field This reduces the effective weak cross sections for relativistic neutrinos as discussed by the authors.
Abstract: A massive Dirac neutrino has a magnetic moment, which causes its spin to precess in a magnetic field This reduces the effective weak cross sections for relativistic neutrinos An estimate on the basis of phenomenological considerations as well as the standard electroweak theory indicates that massive neutrinos from supernovae and neutron stars may contain significant mixtures of negative- and positive-helicity states
442 citations
TL;DR: In this paper, the authors describe a fully relativistic augmented plane wave (APW) method where the basis functions are pure spin functions in the large component, which allows spin-mixing interactions to be separated and treated more efficiently than in the standard APW method.
Abstract: The authors describe a fully relativistic augmented-plane-wave (APW) method where the basis functions are pure spin functions in the large component. This feature allows spin-mixing interactions to be separated and treated more efficiently than in the standard relativistic APW method. These basis functions are constructed by solving an approximate relativistic radial equation. In addition, the energy derivative is used in the construction of the basis functions so that one obtains adequate variational freedom solving a linear secular equation. Both the utility and the limitations of the technique are discussed.
409 citations
TL;DR: In this article, a general method of deriving nonlinear equations of hydrodynamics for both normal liquid and superfluid 4He and 3He, equations of the elasticity theory, equations for spin waves in magnets and spin glasses, liquid crystals, and so on is described.
382 citations
TL;DR: In this article, the Jeener-Broekaert pulse sequence was used to detect deuteron line shapes, from which the orientational distribution of partially ordered solids or solid polymers may be determined.
Abstract: Deuteron spin alignment offers a new possibility to investigate extremely slow rotational motions in solids and solid polymers. A convenient theoretical description of the creation and detection of spin alignment by application of the Jeener–Broekaert pulse sequence is given for both static and slowly time dependent quadrupole coupling, as well as for spin–lattice relaxation of spin alignment. It is shown that the NMR signal following spin alignment yields a correlation function of the time dependent quadrupole coupling. This correlation function is evaluated explicitly for a deuteron on the corner of a regular tetrahedron undergoing tetrahedral jumps. Various applications of deuteron spin alignment are demonstrated experimentally, e.g., its use to obtain undistorted deuteron line shapes, from which the orientational distribution of partially ordered solids or solid polymers may be determined. In solid polyethylene it is shown that not only the deuterons in the crystalline regions but those in the mobile ...
274 citations
238 citations
01 Jan 1980
221 citations
183 citations
TL;DR: The spin fluctuation theory of itinerant-electron magnetism is developed by using the static functional integral method combined with the single-site alloy analogy approximation as discussed by the authors, which is shown to provide an interpolating description of magnetism yielding good results in some important limits; in the weak interaction limit or T = 0 K it reduces to the Hartree-Fock theory, and in the strong coupling limit for the half-filled band it reproduces the results of the molecular field theory.
Abstract: The spin fluctuation theory of itinerant-electron magnetism is developed by using the static functional integral method combined with the single-site alloy analogy approximation. The theory is shown to provide an interpolating description of itinerant electron magnetism yielding good results in some important limits; in the weak interaction limit or T =0 K it reduces to the Hartree-Fock theory, and in the strong coupling limit for the half-filled band it reproduces the results of the molecular-field theory. With the use of the half-filled Bell shape band the temperature dependences of the average moment, the local moment, the susceptibility and the specific heat are calculated numerically for various values of the electron-electron interaction.
TL;DR: In this article, it is argued that it is not necessary for the two-electron molecular orbital integrals and configuration interaction expansion coefficients to be stored in the computer as accurately as they are in present configuration interaction calculations, so these numbers may be kept in the central memory, even for large basis set calculations.
TL;DR: In this article, the Edwards-Anderson model is applied to two-component spin systems, where each spin of the system can take only n directions in a plane and the average degeneracy in the ground state is calculated.
Abstract: For pt.I see ibid., vol.10, no.12, p.2769 (1980). The general theory, developed in the preceding paper to study the ground state properties of spin glasses, is applied to two-component spin systems. As an extension of the Edwards-Anderson model (1975) a system of the two-component spins, each spin of which can take only n directions in a plane ('discrete planar model'), is introduced to count (gn)-the average degeneracy in the ground state. This procedure allows the authors to see how the fundamental properties change by the spin symmetry. For n=2, the theory reproduces the previous results for the Ising model. They can study the XY model as a limit of n to infinity . Precise calculations are performed for the infinite-range exchange interactions. They find (ginfinity )=e0.51691N.
TL;DR: In this article, the authors measured the hysteresis cycle of the magnetization of CuMn 1 % in the spin glass state as a function of the concentration of a non magnetic impurity.
Abstract: 2014 Measurements of the hysteresis cycle of the magnetization of CuMn 1 % in the spin glass state as a function of the concentration of a non magnetic impurity show that the width of the hysteresis is proportional to the concentration of Au at a rate of 6.2 ± 0.4 kOe/at. % Au. A much smaller rate observed for Al and Ag and higher rate observed for Pt demonstrate unambiguously that the spin orbit interaction is responsible for the anisotropy field in the spin glass state. A comparison is made with similar alloys studied by spin resonance by Okuda and Date and some implication are discussed. J. Physique 41 (1980) 427-435 MAI 1980,
TL;DR: In this paper, a spin-fluctuation theory was applied to iron and nickel for a discussion of their magnetic and thermodynamical properties at finite temperatures with a slight extension including the effect of charge fields within the steepest-descent approximation.
Abstract: A spin-fluctuation theory developed previously by the present author is applied to iron and nickel for a discussion of their magnetic and thermodynamical properties at finite temperatures with a slight extension including the effect of charge fields within the steepest-descent approximation. The Curie temperature, the average magnetization, the amplitude of local magnetic moments, the spin susceptibility and the specific heat are calculated, which are in qualitatively, or semi-quantitatively good agreement with experimental data.
TL;DR: In this paper, a stochastic theory of positive muon spin relaxation in a random dilute spin system is formulated to deduce the correlation time of Fe (or Mn) moments.
Abstract: The zero-field spin relaxation of positive muon is measured in spin-glasses AuFe and CuMn. A stochastic theory of muon spin relaxation in a random dilute spin system is formulated to deduce the correlation time of Fe (or Mn) moments. The observed correlation time increases rapidly from 10/sup -10/ sec (atTapprox.1.2T/sub g/) to 10/sup -5/ (at Tapprox.0.5T/sub g/), showing a sharp slowing down of spin fluctuation around T/sub g/.
Journal Article•
TL;DR: In this article, the properties of the spin density fluctuations in the itinerant antiferromagnetic compounds V 3 S 4 and V 5 S 8 have been investigated in both the paramagnetic and the antifromagnetic states by using the pulsed NMR technique.
Abstract: The properties of the spin density fluctuations in the itinerant antiferromagnetic compounds V 3 S 4 and V 5 S 8 have been investigated in both the paramagnetic and the antiferromagnetic states by using the pulsed NMR technique. Although it has been proposed that V 3 S 4 is one of weak itinerant antiferromagnets because of the low ordering temperature, small staggered moment M Q and the temperature dependence of M Q , the temperature dependence of the nuclear spin-lattice relaxation rate 1/ T 1 are not in accord with the prediction based on the self-consistent renormalization theory of spin fluctuations for weak itinerant antiferromagnets. In V 5 S 8 , the observed temperature independent process of 1/ T 1 in the paramagnetic state and the temperature dependences of the bulk susceptibility and M Q are not explained from either weakly magnetic limit or localized moment limit, suggesting this material is in the intermediate magnetic regime.
TL;DR: In this paper, a new collective mode in zero-sound propagation in the Balian-Werthamer state was shown experimentally to split linearly with magnetic field into five components and display the characteristic angular dependence of a $J=2$ multiplet.
Abstract: The recently observed new collective mode in the zero-sound propagation in $^{3}\mathrm{He}$-$B$ is shown experimentally to split linearly with magnetic field into five components and to display the characteristic angular dependence of a $J=2$ multiplet. Agreement with the predicted splitting first computed by Tewordt and Schopohl leads to the identification of the newly found feature with the spin pair-vibration mode of the Balian-Werthamer state.
TL;DR: HAL as mentioned in this paper is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not, which may come from teaching and research institutions in France or abroad, or from public or private research centers.
Abstract: HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. PHASE TRANSITIONS IN A SPIN POLARIZED FLUID : THERMAL EQUILIBRIUM AND KINETIC PHENOMENA P. Nozières
TL;DR: In this article, the longitudinal spin relaxation time T1ρ of protons (1H) in the rotating frame was measured for a spin locking field ranging from 5 to 20 G.
Abstract: Molecular motions and spatial properties of the solid polymer polyethyleneterephthalate have been investigated using high resolution 1H solid state NMR techniques. The longitudinal spin relaxation time T1ρ of protons (1H) in the rotating frame was measured for a spin locking field ranging from 5 to 20 G. The decay of the 1H magnetization indicated the existence of two distinct T1ρ’s and their field dependence shows that they are associated with two mobile phases of the polymer. The 1H magnetization also relaxes under the dipolar narrowed Carr–Purcell (DNCP) multipulse sequence with two dintinct T1y relaxation times. The ratios T1y’s and T1ρ’s deviate significantly from the expected theoretical values. The combined experiment with magic angle spinning and the DNCP sequence followed by homonuclear dipolar decoupling reveals the individual T1y relaxation of the resolved methylene and aromatic protons. These two species of protons were found to relax with the same T1y’s, thus implying that spin diffusion must have taken place under the homonuclear dipolar decoupling multipulse. The qualitative description of spin diffusion under homonuclear decoupling is given. The combined experiment with spin locking and the DNCP sequence yields the correspondence between the two T1ρ’s and the two T1y’s. The long T1ρ corresponds to the short T1y whereas the short T1ρ corresponds to the long T1y. Communication between the two spatial phases via spin diffusion was also observed in this experiment by monitoring the recovery of the 1H magnitization associated with the short T1ρ after it has been eliminated during the spin locking. The total 1H magnetization is allowed to equilibrate in the laboratory frame for a variable time much shorter than T1 after the spin locking field has been turned off. The spatial relationship between the two phases is discussed.
TL;DR: In this paper, the total set of all one-loop diagrams for scattering of spin - 1 2 fermions is calculated based on a gauge model of the electroweak interaction, which allows us to use the expression obtained at arbitrary high energies where weak and electromagnetic interaction strengths are comparable.
TL;DR: The general effective radial potentials for a spin-1/2 particle interacting with scalar, electric, and magnetic potentials are given in this paper, where it is shown that the magnetic potential provides a well deep enough to confine the massless particle.
Abstract: The general effective radial potentials for a spin‐ 1/2 particle interacting with scalar, electric, and magnetic potentials are given. In the m=0 limit, it is shown that the magnetic potential provides a well deep enough to confine the massless particle. In particular, there are exact zero‐energy solutions in which two of the four components of the massless particle are confined; only two can leak out into the asymptotic region. The scattering amplitude is analytic in the entire j plane, hence consists only of Regge poles.
TL;DR: In this paper, it was shown that there exists a spin c structure for which there exist a pair of covariantly constant spinors, which are used to generate eigenfunctions of higher spin from scalar eigen functions carrying an electric charge.
TL;DR: In this paper, a method for direct configuration interaction (CI) calculations with a multiconfigurational reference function is described, where the reference state can contain several closed-shell electronic configurations and the CI expansion comprises all single and double replacements out of all these configurations.
Abstract: A method for direct configuration–interaction (CI) calculations with a multiconfigurational reference function is described. The reference state can contain several closed-shell electronic configurations and the CI expansion comprises all single and double replacements out of all these configurations. The resulting secular problem is solved using a variation-perturbation method. A number of examples are given showing the efficiency of the method. The largest CI expansion used in calculations with this program so far contains 76,471 spin- and space-symmetrized configurations.
TL;DR: In this paper, the effect of the charge density fluctuation was taken into account within the saddle point approximation, and the results of numerical calculations for various model densities of states including those for bcc and fcc d-metals were presented.
TL;DR: In this article, the authors investigate what models can be invented by thinking of quarks and leptons as composites of spin-1 2 subcomponents confined into singlets of a new SU(3) (subcolor).
TL;DR: In this article, the one-dimensional classical planar antiferromagnet in an applied magnetic field in the plane of the planar spin is analyzed theoretically, and the transverse and longitudinal spin correlation lengths are calculated.
Abstract: The one-dimensional classical planar antiferromagnet in an applied magnetic field in the plane of the planar spin is analyzed theoretically. Solving the transfer matrix equation, we calculate the transverse and the longitudinal spin correlation lengths. The dynamical structure factors are also determined. The transverse spin fluctuations are dominated by the multisoliton term, while the longitudinal spin fluctuations are dominated by a single magnon term.
TL;DR: In this paper, the authors make reasonable predictions of the MIT bag model for the masses, spin and electromagnetic splittings of D, B, Σ c and ∧ c.
TL;DR: In this paper, the spin structures in the three ordered phases which appear in the concentration versus transition temperature phase diagram, namely, the Fe-rich and Co-rich antiferromagnetic phases and the new phase are determined.
Abstract: Neutron diffraction experiment has been done on a randomly mixed antiferromagnet with competing spin anisotropies, Fe (1- x ) Co x Cl 2 . Front the experiment the spin structures in the three ordered phases which appear in the concentration versus transition temperature phase diagram, namely, the Fe-rich and Co-rich antiferromagnetic phases and the new phase are determined. The spin structure in the Fe-rich (Co-rich) phase is essentially identical with that of pure FeCl 2 (CoCl 2 ). In the new phase, although overall spin structure is the same as those of the pure materials, both of the two spin components are observed which are associated with competing anisotropies. The new phase is an OAF phase in the sense that an inclination of the sublattice magnetizations both from the easy axes of the pure substances means the simultaneous ordering of the spin components. The temperature dependences, of the spin components are discussed in favour of the result of the renormalization group theory.