17 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Knight Shift"  
Results: 1 - 17
open access

Theory of exotic superconductivity and normal states of heavy electron and high temperature superconductivity materials. Progress report, February 15, 1994--February 14, 1995

Description: This is a progress report for the DOE project covering the period 2/15/94 to 2/14/95. The PI had a fruitful sabbatical during this period, and had some important new results, particularly in the area of new phenomenology for heavy fermion superconductivity. Significant new research accomplishments are in the area of odd-in-time-reversal pairing states/staggered superconductivity, the two-channel Kondo lattice, and a general model for Ce impurities which admits one-, two-, and three-channel Kond… more
Date: February 1, 1995
Creator: Cox, D. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The selective hydrogenation of crotonaldehyde over bimetallic catalysts

Description: The selective hydrogenation of crotonaldehyde has been investigated over a monometallic Pt/SiO{sub 2} catalyst and platinum bimetallic catalysts where the second metal was either silver, copper, or tin. The effects of addition of a second metal to the Pt/SiO{sub 2} system on the selectivity to crotyl alcohol were investigated. The Pt-Sn bimetallic catalysts were characterized by hydrogen chemisorption, {sup 1}H NMR and microcalorimetry. The Pt-Ag/SiO{sub 2} and Pt-Cu/SiO{sub 2} catalysts were c… more
Date: February 1, 1997
Creator: Schoeb, A. M.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

The Search for Magnetic Order in delta-Pu metal using muon spin relaxation

Description: We review results from previous muon spin relaxation ({mu}SR) measurements in applied fields of H{sub 0} = 0 and 0.25 T which established an upper limit for the ordered or disordered frozen spin moment above T = 4 K in {delta}-Pu (4.3 at. % Ga) of {micro}{sub ord} {le} 10{sup -3} {mu}{sub B}. In addition, we present new data in H{sub 0} = 0.25 T and 2 T applied field on a highly annealed {delta}-Pu (4.3 at. % Ga) sample. Neither the muon Knight shift (H{sub 0} = 2 T) nor the inhomogeneous linew… more
Date: October 16, 2006
Creator: Heffner, R; Ohishi, K; Fluss, M; Morris, G; MacLaughlin, D; Shu, L et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Hybridization-driven gap in U3Bi4Ni3: a 209Bi NMR/NQR study

Description: We report {sup 209}Bi nuclear-magnetic-resonance and nuclear-quadrupole-resonance measurements on a single crystal of the Kondo insulator U{sub 3}Bi{sub 4}Ni{sub 3}. The {sup 209}Bi nuclear-spin-lattice relaxation rate (T{sub 1}{sup -1}) shows activated behavior and is well fit by a spin gap of 220 K. The {sup 209}Bi Knight shift (K) exhibits a strong temperature dependence arising from 5f electrons, in which K is negative at high temperatures and increases as the temperature is lowered. Below … more
Date: January 1, 2009
Creator: Baek, Seung H
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Theory of the Knight Shift and Flux Quantization in Superconductors

Description: Consequences of a generalization of the theory of superconductivity that yields a finite Knight shift are presented. In this theory, by introducing an electron-electron interaction that is not spatially invariant, the pairing of electrons with varying total momentum is made possible. An expression for Xs (the spin susceptibility in the superconducting state) is derived. In general Xs is smaller than Xn, but is not necessarily zero. The precise magnitude of Xs will vary from sample to sample and… more
Date: May 1, 1962
Creator: Cooper, L. N.; Lee, H. J.; Schwartz, B. B. & Silvert, W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Muon spin relaxation in CeCu/sub 2/Si/sub 2/ and muon Knight shift in various heavy-fermion systems

Description: Positive muon spin precession has been observed in varius heavy-fermion systems in the transverse external magnetic field. In the superconductor CeCu/sub 2.1/Si/sub 2/, the relaxation rate of muon spins increases rapidly with decreasing temperature below T/sub c/. This is interpreted as the results of the inhomogeneous fields due to the imperfect penetration of the external field into the type-II superconducting state. The magnetic-field penetration depth lambda is derived from the observed muo… more
Date: January 1, 1986
Creator: Uemura, Y. J.; Kossler, W. J.; Hitti, B.; Kempton, J. R.; Schone, H. E.; Yu, X. H. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Muon Spin Relaxation and Knight Shift in the Heavy-Fermion Superconductor UPt3

Description: Positive muon spin relaxation experiments have been conducted on the heavy-fermion superconductor UPt/sub 3/ in both the normal and superconducting states for zero, transverse, and longitudinally applied magnetic fields. Below 6 K in zero applied field, the ..mu../sup +/ relaxation rate is approximately twice that expected from /sup 195/Pt nuclear dipolar relaxation alone. Transverse- and longitudinal-field measurements show that the observed relaxation rate depends on magnetic field and is qua… more
Date: January 1, 1986
Creator: Cooke, D. W.; Heffner, R. H.; Hutson, R. L.; Schillaci, M. E.; Smith, J. L.; Willis, J. O. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

/sup 17/O NMR study of YBa/sub 2/Cu/sub 3/O/sub 7/minus/delta/

Description: We present our /sup 17/O NMR experimental results in a magnetically aligned powder sample of YBa/sub 2/Cu/sub 3/O/sub 7/minus/delta/ (T/sub c/ = 93 K). The sign of the anisotropic Knight Shift shows that the spin density resides mainly on the p/sub sigma/ orbitals at the planar O(2,3) and bridging O(4) sites. About 30 % of the total spin susceptibility is attributed to the oxygen 2p/sub sigma/ states. The Knight shift at the O(2,3) sites decreases more rapidly than that at the chain O(1) sites,… more
Date: January 1, 1989
Creator: Takigawa, M.; Hammel, P. C.; Heffner, R. H.; Fisk, Z.; Ott, K. C. & Thompson, J. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Copper and oxygen NMR studies on the magnetic properties of YBa sub 2 Cu sub 3 O sub 7-y

Description: Microscopic magnetic properties of the CuO{sub 2} layers in YBa{sub 2}Cu{sub 3}O{sub 7-y} have been investigated from Cu and O NMR experiments on the y{approx equal}0 (T{sub c}=92K) and y=0.37 (T{sub c}=62K) materials. The Knight shift at the planar Cu and the planar oxygen sites are found to be proportional to a common spin susceptibility {chi}{sub s} which depends on temperature and oxygen-content, strongly supporting a single component spin model for the CuO{sub 2} planes. In the y=0.37 mate… more
Date: January 1, 1989
Creator: Takigawa, Masashi.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

{sup 209}Bi NMR in heavy-electron system YbBiPt

Description: Bismuth NMR Knight shift and spin lattice relaxation rate 1/T{sub 1} are reported between 35--325K in the low-carrier heavy fermion system YbBiPt. The Knight shift is strongly temperature dependent and negative. Its temperature dependence tracks the bulk susceptibility with a hyperfine coupling constant A{sub hf} = {minus}7.89 kOe/{mu}B. At low temperatures 1/T{sub 1} exhibits a dramatic increase, such that the average 4f spin correlation time {tau}{sub f} shows a crossover behavior at about 75… more
Date: June 1, 1994
Creator: Reyes, A. P.; Le, L. P.; Heffner, R. H.; Ahrens, E. T.; Fisk, Z. & Canfield, P. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

NMR studies of oxygen-doped La{sub 2}CuO{sub 4+{delta}}

Description: The observation that the structure of this material is sensitive to levels of doping sufficient to produce superconductivity ({Tc} {approximately}40 K) suggests an important role for structure in determining its electronic properties. Here we discuss unusual features of phase separation and studies of cooling rate dependence of the superconducting {Tc} relevant to this proposition.
Date: August 11, 1993
Creator: Hammel, P. C.; Reyes, A. P.; Ahrens, E. T.; MacLaughlin, D. E.; Thompson, J. D.; Fisk, Z. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

NMR of small platinum particles

Description: /sup 195/Pt NMR lineshapes as well as relaxation data are presented in three different samples of platinum metal particles (46%, 26%, and 15% dispersion) supported on alumina. The electronic properties of these particles are very much different from that of bulk Pt metal. A prominent peak in the lineshape has been identified as a surface resonance which arises from Pt nuclei on the surface of the Pt particles. We find that these surface Pt atoms are non-metallic when coated with adsorbed molecu… more
Date: January 1, 1980
Creator: Stokes, H. T.; Rhodes, H. E.; Wang, P. K; Slichter, C. P. & Sinfelt, J. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Nuclear magnetic resonance and the question of 5F electron localization in the actinides

Description: Nuclear magnetic resonance results are presented for a number of NaCl-type compounds and cubic Laves-phase type compounds of uranium, neptunium, and plutonium. Special emphasis is placed on the Knight shift and spin-lattice relaxation time measurements and their interpretation in terms of localized or itinerant pictures of the 5Line integral electrons.
Date: January 1, 1976
Creator: Fradin, F. Y.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen