Showing papers on "Spin density wave published in 1979"
TL;DR: In this paper, the functional integral method of the previous paper is generalized to allow a discussion of the dynamical spin fluctuations in itinerant-electron magnets, and the magnitude fluctuations and nonstatic spin fluctuations are treated as a perturbation on the nonlinearly interacting static spin fluctuations.
Abstract: The functional-integral method of the previous paper is generalized to allow a discussion of the dynamical spin fluctuations in itinerant-electron magnets. The magnitude fluctuations and nonstatic spin fluctuations are treated as a perturbation on the nonlinearly interacting static spin fluctuations. The result is a free energy which is a sum of a Stoner contribution together with correlation corrections, a classical Heisenberg free energy as found in the previous paper, and a quantum spin-wave free energy minus its zero-frequency part.
55 citations
TL;DR: In this article, the magnetic excitations of the incommensurate spin-density wave in pure chromium have been investigated with use of inelastic neutron scattering, and the polarizations of these modes are found to be highly anisotropic.
Abstract: The magnetic excitations of the incommensurate spin-density wave in pure chromium have been ivestigated with use of inelastic neutron scattering. We have observed the spin wave modes originating from the incommensurate magnetic Bragg reflections. The polarizations of these modes are found to be highly anisotropic. We have also observed a new magnetic excitation centered at a commensurate wave vector. This new excitation is interpreted as a feature specific to a transverse incommensurate spin-density wave.
42 citations
TL;DR: In this article, a spin density wave host, Cr and Cr-Mo 2, each containing 14% Fe, was used for neutron scattering, transport and magnetic measurements on two spin-density wave hosts, and the results showed that antiferromagnetism and spin glass ordering coexist at low temperatures.
Abstract: Neutron scattering, transport and magnetic measurements are presented on two spin density wave hosts, Cr and Cr-Mo 2%, each containing 14% Fe. The results show that in both systems antiferromagnetism and spin glass ordering coexist at low temperatures.
34 citations
TL;DR: In this article, the wave number dependent susceptibility χ(q) in the superconducting state for (i) clean superconductor, (ii-1) dirty super-conductor with weak spin-orbit scattering, and (iii-2) dirty single-antenna superconductors with strong spinorbit scattering was investigated.
20 citations
12 citations
TL;DR: In this article, changes of the Q-vector with temperature and pressure occur in the electron-hole k-state pairing model even when no changes occur in Fermi surface nesting vectors.
10 citations
TL;DR: The resistivity minimum in Cr -4.0 at.% Co alloy is found to deepen first with pressure up to 6.2 kbar and to shallow rapidly to vanish at about 17 kbar.
8 citations
8 citations
TL;DR: In this paper, the integrated intensity of spin waves decreases slowly with falling temperature, contrary to the rapid decrease found in the incommensurate spin density wave (SDW) phase and also quite different from the rapid increase in the commensurate SDW phase of the Cr-Mn alloy.
6 citations
TL;DR: In this article, a simplified model Hamiltonian is proposed to calculate the magnetic susceptibility of chromium containing small amounts of Fe impurity, which takes account of nearest neighbor exchange coupling of the local moments as well as their coupling to the spin density wave of the Cr host.
Abstract: Recent studies of the magnetic susceptibility of chromium containing small amounts (<5%) of Fe impurity indicate that in the dilute limit the major contribution to the susceptibility comes from small clusters of Fe moments interacting among themselves via a strong ferromagnetic exchange coupling. We present a calculation of the susceptibility based upon a simplified model Hamiltonian which takes account of nearest neighbor exchange coupling of the local moments as well as their coupling to the spin density wave of the Cr host. In order to obtain reasonable quantitative agreement with experiment, the model requires a strong interaction between the moments and the spin density wave. We also find that moment pairs make the most substantial contribution to the overall susceptibility.
3 citations
TL;DR: In this article, a phenomenological theory of charge and spin density waves at surfaces is presented, where the density wave is described by an order parameter which obeys an equation similar to that proposed by Ginzburg and Landau for superconductivity.
Abstract: A phenomenological theory of charge and/or spin density waves at surfaces is presented. The density wave is described by an order parameter which obeys an equation similar to that proposed by Ginzburg and Landau for superconductivity. A condition is obtained for the existence of density waves in terms of two parameters. These are computed for a simple model antiferromagnet and the results are used to estimate the transition temperature of surface antiferromagnetism in chromium and chromium alloys. Other materials are also discussed.
TL;DR: In this article, the authors show the importance of the reconstruction energies on the actinide properties both in solid state and solutions and analyze the influence of the excitation energy on the stability and geometry.
Abstract: The main purpose of this paper is to show the importance of the reconstruction energies on the actinide properties both in solid state and solutions. As a consequence of the specific dualism localization-delocalization of the 5f and 6d electrons, charge waves can occur in crystal compounds at low temperature. In an extended two-band Hubbard model which takes into account the intra- and inter-site Coulomb interactions as well as the kinetic energy, the criteria for the occurrence of the charge and orbital waves are obtained. Orbital ordering can be accompanied by spin density wave formation. Partial attention is given to the occurrence of supraconductivity, it is proposed that electron pair formation in a mixed valence state is one of the important mechanisms of supraconductivity state formation. The influence of the excitation energy on the stability and geometry is analysed. Estimates of the Cm(IV-V), Cm(V-VI) and Cm(VI-VII) oxidation potentials are given. It is shown that distortion from the linear to the bent structure is possible for AnO+2 cations.
1 Jan 1979
TL;DR: In this article, it is suggested that in the fluctuation regime above the spin-Peierls instability, a sliding spin density wave can be put into motion by means of an inhomogeneous magnetic field.
Abstract: It is suggested that in the fluctuation regime above the spin-Peierls instability a sliding spin density wave can be put into motion by means of an inhomogeneous magnetic field.
TL;DR: In this article, a phenomenological theory of surface spin-density waves is applied to the Cr-Re alloy and it is found that surface spin density waves may exist on the surface of this alloy at temperatures up to 0.9K above the bulk transitions temperature.
Abstract: A phenomenological theory of surface spin-density waves is applied to the Cr-Re alloy. It is found that surface spin-density waves may exist on the surface of this alloy at temperatures up to 0.9K above the bulk transitions temperature TN.
1 Jan 1979
TL;DR: In this article, the Anderson-Maki theorem was generalized to all types of order in one-dimensional systems, including charge density wave, spin density wave and triplet superconductivity.
Abstract: It has long been known that disorder or the presence of impurities cause localization of the single-electron states in one-dimensional systems (1). In addition to this we shall show that such impurities, in general, can have a large effect upon the degree of order which tends to appear as T→O and upon the mean field transition temperature T of any such ordered phases. However, this effect is selective and depending upon the nature of the scattering introduced by the impurities can severely suppress one type of order while leaving another virtually unaffected. The result which we obtain is a generalization to all types of order in one-dimensional systems, of the Anderson-Maki theorem(2,3) on the insensitivity of the singlet superconducting transition temperature to the presence of non-magnetic impurities, while showing a marked depression of Tc with increasing number of mangetic impurities. We show that to each type of ordered state in one dimension, whether it be a charge density wave (CDW), spin density wave (SDW), triplet superconductivity (TS) or singlet superconductivity (SS) there exists a type of impurity scattering mechanism which has a negligible effect upon the mean field transition temperature of this state.