Topic

# Knight shift

About: Knight shift is a research topic. Over the lifetime, 2347 publications have been published within this topic receiving 36853 citations.

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TL;DR: In this paper, the polarization of conduction electrons due to the first order perturbed energy corresponding to the Fr\"ohlich-Nabarro and Zener mechanism was investigated and it was shown that the polarization is concentrated in the neighborhood of the Mn ions.

Abstract: The polarization of conduction electrons due to $s\ensuremath{-}d$ interaction in CuMn alloys is investigated. The uniform polarization due to the first order perturbed energy corresponding to the Fr\"ohlich-Nabarro and Zener mechanism is shown to be completely modified by the first order perturbation of the wave functions and the polarization is concentrated in the neighborhood of the Mn ions. At the same time it is shown that the Fr\"ohlich-Nabarro interaction is included in the Ruderman-Kittel result as one component. The electronic $g$-value of Mn ions and the Knight shift of the Cu-nuclei are also discussed from this point of view.

2,274 citations

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TL;DR: In this paper, a general review of experimental work is presented in order to permit a comprehensive evaluation of current understanding of the quantum size effect on the electronic spectrum including magnetic susceptibility, nuclear magnetic resonance, electron spin resonance, heat capacity, optical, and infrared absorption measurements.

Abstract: The subject of small metallic particle properties is outlined with emphasis on quantum electronic effects. The theoretical background for interpretation of experiments is discussed beginning with the work of Kubo. More recent amendments to this have been included, taking into account the techniques of random matrix theory and effects of the spin-orbit interaction. A general review of experimental work is presented in order to permit a comprehensive evaluation of current understanding of the quantum size effect on the electronic spectrum. This survey includes magnetic susceptibility, nuclear magnetic resonance, electron spin resonance, heat capacity, optical, and infrared absorption measurements. These are discussed in many instances from the point of view of there being competing size effects arising from a reduced volume contrasted with those from the surface. A number of stimulating and provocative results have led to the development of new areas of research involving metallic clusters such as cluster beam techniques, far-infrared absorption by particle clusters, adsorbate NMR, and particle-matrix composites. Although there is little question that the experiments themselves indicate the existence of quantum effects, there are as yet, insufficient results to test the theoretical predictions for electron-level distribution functions based on fundamental symmetries of the electron Hamiltonian. A new suggestion for measurement of the electron-level correlation function is made using the magnetic field dependence of the NMR Knight shift. Particle preparation methods are also reviewed with commentary on the problems and advantages of these techniques for investigation of quantum electronic effects.

1,153 citations

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TL;DR: In this paper, the authors used 17O NMR to determine the spin susceptibility of the layered oxide superconductor Sr2RuO4 and showed no change in spin susceptibility on passing through the superconducting transition temperature.

Abstract: Superconductivity — one of the best understood many-body problems in physics — has again become a challenge following the discovery of unconventional superconducting materials: these include heavy-fermion1, organic2 and the high-transition-temperature copper oxide3 superconductors In conventional superconductors, the electrons form superconducting Cooper pairs in a spin-singlet state, which has zero total spin (S = 0) In principle, Cooper pairs can also form in a spin-triplet state (S = 1), analogous to the spin-triplet ‘p-wave’ state of paired neutral fermions in superfluid 3He (ref 4) At present, the heavy-fermion compound UPt3 is the only known spin-triplet superconductor5,6, although the layered oxide superconductor Sr2RuO4 (ref 7) is believed, on theoretical grounds8, to be a promising candidate The most direct means of identifying the spin state of Cooper pairs is from measurements of their spin susceptibility, which can be determined by the Knight shift (as probed by nuclear magnetic resonance (NMR)) Here we report Knight-shift measurements of Sr2RuO2 using 17O NMR Our results show no change in spin susceptibility on passing through the superconducting transition temperature, which provides the definitive identification of Sr2RuO4 as a spin-triplet superconductor

755 citations

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TL;DR: A theory of the superconducting state for 2D metals without inversion symmetry modeling the geometry of a surfacesuperconducting layer in a field-effect transistor or near the boundary doped by adsorbed ions is developed.

Abstract: Motivated by recent experimental findings, we have developed a theory of the superconducting state for 2D metals without inversion symmetry modeling the geometry of a surface superconducting layer in a field-effect transistor or near the boundary doped by adsorbed ions. In such systems the twofold spin degeneracy is lifted by spin-orbit interaction, and singlet and triplet pairings are mixed in the wave function of the Cooper pairs. As a result, spin magnetic susceptibility becomes anisotropic and Knight shift retains finite and rather high value at T = 0.

713 citations

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TL;DR: In this paper, the authors examined the temperature dependence of the NMR Knight shift and relaxation rate, entropy, resistivity, infrared conductivity, Raman scattering, ARPES and tunnelling data and concluded that the second scenario is not at all supported.

Abstract: Underdoped high- T c superconductors are frequently characterised by a temperature, T * , below which the normal-state pseudogap opens. Two different “phase diagrams” based on the doping ( p ) dependence of T * are currently considered: one where T * falls to zero at a critical doping state and the other where T * merges with T c in the overdoped region. By examining the temperature dependence of the NMR Knight shift and relaxation rate, entropy, resistivity, infrared conductivity, Raman scattering, ARPES and tunnelling data, it is concluded that the second scenario is not at all supported. Neither can one distinguish a small and a large pseudogap as is often done. T * is an energy scale, which falls abruptly to zero at p =0.19. Colour figures are available at cond-mat/0005063.

548 citations