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We report NMR spectrum analysis for CrAs, which was recently reported to be superconducting under pressure. The NMR spectrum obtained by the powdered single crystals shows a typical powder pattern reproduced by the electric field ...
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We report NMR spectrum analysis for CrAs, which was recently reported to be superconducting under pressure. The NMR spectrum obtained by the powdered single crystals shows a typical powder pattern reproduced by the electric field gradient (EFG) parameters and isotropic Knight shift, indicating anisotropy of Knight shift is not remarkable in CrAs. For the oriented sample, the spectrum can be understood by considering that the crystals are aligned for H parallel to b. The temperature dependence of Knight shift was successfully obtained from NMR spectrum with large nuclear quadrupole interaction.
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A description of a muon spin-polarization behavior in condensed media with polarized nuclei is given. These objects could be obtained at low temperatures (T less than or equal to 0.03 K) and in external magnetic fields B similar t...
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A description of a muon spin-polarization behavior in condensed media with polarized nuclei is given. These objects could be obtained at low temperatures (T less than or equal to 0.03 K) and in external magnetic fields B similar to 20 kG. It is shown that the mu SR-technique gives in this case new opportunities for a precise study of a muon diffusion in metal lattices and an accurate measurement of the Knight shift at the muon. Moreover, mu SR gives new opportunities to measure low temperatures and to get a good accuracy for measurements of the magnetic moments of some nuclei. (C) 2000 Published by Elsevier Science B.V. All rights reserved. [References: 4]
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The temperature-independent orbital Knight shifts for the orthorhombic Cu-63(2+)(1) site in YBa2Cu4O8 (Y124) are investigated by utilizing the high order perturbation formulae of these parameters for a 3d(9) ion situated into orth...
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The temperature-independent orbital Knight shifts for the orthorhombic Cu-63(2+)(1) site in YBa2Cu4O8 (Y124) are investigated by utilizing the high order perturbation formulae of these parameters for a 3d(9) ion situated into orthorhombically elongated octahedra. The calculation results are in good agreement with the experimental data. The moderate quasi-axial anisotropies of the Knight shifts are ascribed to the elongation distortion of the four-fold coordinated Cu2+(1) site. The g factors are also theoretically calculated in a uniform way for further experimental verification.
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Westudy the nuclearmagnetic resonance (NMR) properties of graphene. The interaction between nuclear spins and the orbital motion of Dirac electrons is strongly modified by the linear electronic dispersion with respect to its canon...
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Westudy the nuclearmagnetic resonance (NMR) properties of graphene. The interaction between nuclear spins and the orbital motion of Dirac electrons is strongly modified by the linear electronic dispersion with respect to its canonical form. The NMR shift and spin-lattice relaxation time are calculated as function of temperature, chemical potential, and magnetic field for clean and impure graphene, and three distinct regimes are identified: Fermi-, Dirac-gas, and extreme quantum limit (EQL) behaviors. A critical spectrometer assessment shows that NMR is within reach for fully ~(13)C enriched graphene of reasonable size.
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We have performed ~(75)As nuclear magnetic resonance (NMR) Knight shift measurements on single crystals of NaFe_0.975Co_0.025 As to show that its superconductivity is a spin-paired, singlet state consistent with predictions of the...
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We have performed ~(75)As nuclear magnetic resonance (NMR) Knight shift measurements on single crystals of NaFe_0.975Co_0.025 As to show that its superconductivity is a spin-paired, singlet state consistent with predictions of the weak-coupling BCS theory. We use a spectator nucleus, ~(23)Na, uncoupled from the superconducting condensate, to determine the diamagnetic magnetization and to correct for its effect on the ~(75)As NMR spectra. The resulting temperature dependence of the spin susceptibility follows the Yosida function as predicted by BCS for an isotropic, single-valued energy gap. Additionally, we have analyzed the ~(23)Na spectra that become significantly broadened by vortices to obtain the superconducting penetration depth as a function of temperature with λ_(ab)(0) = 5327 ± 78 A.
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We have performed ~(75)As and ~(23)Na nuclear magnetic resonance (NMR) measurements on a single crystal of NaFe_(0.9835)Co_(0.0165)As and found microscopic coexistence of superconductivity with a two-component spin density wave (S...
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We have performed ~(75)As and ~(23)Na nuclear magnetic resonance (NMR) measurements on a single crystal of NaFe_(0.9835)Co_(0.0165)As and found microscopic coexistence of superconductivity with a two-component spin density wave (SDW). Using ~(23)Na NMR we measured the spatial distribution of local magnetic fields. The SDW was found to be incommensurate with a major component having magnetic moment (～0.2 μ_B/Fe) and a smaller component with magnetic moment (～0.02 μ_B/Fe). Spin lattice relaxation experiments reveal that this coexistence occurs at a microscopic level.
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The ~7Li NMR Knight shift was measured for liquid Li-Tl alloys. Prior to this NMR measurement, DSC measurements were carried out to know the exact liquidus temperatures. Except for some trivial points, the phase diagram determined...
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The ~7Li NMR Knight shift was measured for liquid Li-Tl alloys. Prior to this NMR measurement, DSC measurements were carried out to know the exact liquidus temperatures. Except for some trivial points, the phase diagram determined is almost same as the reported one; the solid compound at the maximum liquidus temperature was observed at 50 at percent Tl; the eutectic point was detected at 84.8 at percent Tl. The 7Li Knight shift, K. decreases rapidly with the addition of Tl up to 20 at percent Tl. In the concentration range from 20 to 50 at percent Tl, the K keeps almost constant value, which is 60 percent of ~7Li Knight shift for the pure liquid Li. Such a decrease of the K is considered as an indication for the strong charge transfer from Li to Tl. The Zintl ion formation is expected in this concentration range of liquid Li-Tl alloys. These tendencies are similar to the previous studies for liquid Li-Ga and Li-In alloys. However, beyond 50at percent Tl, the K increases slightly and reaches to the constant value (70 percent of ~7Li Knight shift for the pure liquid Li). Such a back donation of charge is absent for liquid Li-Ga and Li-In alloys. It is considered that the tendency of the Zintl ion formation for liquid Li-Tl alloys is slightly weaker compared with the cases of liquid Li-Ga and Li-In alloys.
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The 7{left sup}Li NMR Knight shift was measured for liquid Li-Tl alloys, Prior to this NMR measurement, DSC measurements were carried out to know the exact liquidus temperatures, Except for some trivial points, the phase diagram d...
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The 7{left sup}Li NMR Knight shift was measured for liquid Li-Tl alloys, Prior to this NMR measurement, DSC measurements were carried out to know the exact liquidus temperatures, Except for some trivial points, the phase diagram determined is almost same as the reported one; the solid compound at the maximum liquidus temperature was observed at 50 at% Tl; the eutectic point was detected at 84.8 at% TL The 7{left sup}Li Knight shift, K, decreases rapidly with the addition of Tl up to 20 at% Tl. In the concentration range from 20 to .50 at% Tl, the K keeps almost constant value, which is 60% of 7{left sup}Li Knight shift for the pure liquid Li. Such a decrease of the K is considered as an indication for the strong charge transfer from Li to Tl, The Zintl ion formation is expected in this concentration range of liquid Li-Tl alloys. These tendencies are similar to the previous studies for liquid Li-Ga and Li-In alloys. However, beyond 50at% Tl, the K increases slightly and reaches to the constant value (70% of 7{left sup}Li Knight shift for the pure liquid Li), Such a back donation of charge is absent for liquid Li-Ga and Li-In alloys. It is considered that the tendency of the Zintl ion formation for liquid Li-Tl alloys is slightly weaker compared with the cases of liquid Li-Ga and Li-In alloys.
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Pr, with a dhcp crystal structure, possesses a strongly anisotropic bulk magnetic susceptibility #chi#. The temperature dependencies of #chi#_(||) (applied magnetic field H_(ext) parallel to c axis) and #chi#_(perpendicular) (fiel...
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Pr, with a dhcp crystal structure, possesses a strongly anisotropic bulk magnetic susceptibility #chi#. The temperature dependencies of #chi#_(||) (applied magnetic field H_(ext) parallel to c axis) and #chi#_(perpendicular) (field perpendicular to c axis) are quite different; they can be described by two distinct Curie-Weiss forms at high temperature. Transverse-field (TF) #mu# SR measurements have been performed in a single-crystal Pr sample. In the studied temperature range (1.8收起
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In the nuclear magnetic resonance (NMR) configuration with perpendicular constant (dc) field and radiofrequency (rf) magnetic field, a strong screening supercurrent is generated by the rf field. In order to estimate this current w...
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In the nuclear magnetic resonance (NMR) configuration with perpendicular constant (dc) field and radiofrequency (rf) magnetic field, a strong screening supercurrent is generated by the rf field. In order to estimate this current which may influence Knight shift data, we performed a model experiment in the NMR configuration on a YBa2Cu4O8 single crystal. The differential magneto-optical imaging technique is used to determine the ac screening current distribution in the sample. We find that at T > 20 K, NMR experiments can be straightforwardly interpreted. At T < 20 K, the rf field is completely excluded. In this situation, NNIR only probes the crystal edges; moreover, the Knight shift may be affected by the supercurrent flow. (c) 2007 Elsevier B.V. All rights reserved.
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