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31.
W. J. Kossler X. H. Yu A. Greer H. E. Schone C. E. Stronach M. Davis R. S. Cary W. F. Lankford A. Moodenbaugh J. Oostens 《Hyperfine Interactions》1991,63(1-4):253-258
Transverse-and zero-field μSR measurements have been made for YBa2(Cu1−x
Fe
x
)3O7 withx=0.04, 0.08 and 0.12. The temperature range studied was from approximately 7.5 K to 100 K. The onset of magnetic ordering
commences at about 7.5 K forx=0.04, 10 K forx=0.08 and 20 K forx=0.12. The Gaussian depolarization parameter, σ ofG
x
(t) = exp(−σ2
t
2/2), is depressed by a factor of about 0.6 forx=0.04, but for thex=0.08 sample σ is depressed by a factor of 10 and increasing suppression is seen as the temperature is lowered below 45 K.
This decrease in σ is interpreted in terms of decreasing electronic mean free paths. 相似文献
32.
C.E. Stronach H.S. Plendl H.O. Funsten W.J. Kossler B.J. Lieb V.G. Lind 《Nuclear Physics A》1978,308(3):290-304
Prompt γ-rays from the interactions of stopped π? and of fast π? and π+ near the Δ(1232) resonance with natCa were detected with a Ge(Li) detector in coincidence with incident pions. Yields and cross sections for excitation of residual states as well as recoil momenta were determined and were corrected for γ-feeding. The results of the three experiments show the same general pattern but differ in some specific features. 相似文献
33.
O. Hartmann E. Karlsson R. Wäppling A. Gustavsson-Seidel D. Richter R. Hempelmann W. J. Kossler B. Hitti J. Kempton W. F. Lankford C. E. Stronach 《Hyperfine Interactions》1986,31(1-4):241-245
We have studied the muon diffusion in various Nb−HX systems with 0.75<x<0.95, with special attention to the concentrations x<0.9. For x>0.9 the muon linewidth as function of
temperature has a smooth behaviour and the muon mobility is strongly correlated to the hydrogen diffusion in the beta phase.
The activation energy for the μ+ diffusion is 160 meV, which is lower than that for protons. At hydrogen concentrations below 0.9, the muon diffusion behaviour
is more complicated, and the influence of Nb−H phase transitions is evident. The implications for the local environment of
the muon are discussed. 相似文献
34.
Kossler Penny H. Steenbock O. Folin Fred F. Flauders und Theodor Hryntschak 《Fresenius' Journal of Analytical Chemistry》1914,53(2):140-141
Ohne Zusammenfassung 相似文献
35.
Y. J. Uemura W. J. Kossler B. Hitti J. R. Kempton H. E. Schone X. H. Yu C. E. Stronach W. F. Lankford D. R. Noakes R. Keitel M. Senba J. H. Brewer E. J. Ansaldo Y. Oonuki T. Komatsubara G. Aeppli E. Bucher J. E. Crow 《Hyperfine Interactions》1986,31(1-4):413-418
Positive muon spin precession has been observed in various heavy-fermion systems in the transverse external magnetic field.
In the superconductor CeCu2.1Si2, the relaxation rate of muon spins increases rapidly with decreasing temperature below TC. 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 λ is derived from the observed muon spin relaxation
rate. λ is about 1200 ∢ at T∼0.5TC, and the temperature dependence of λ is consistent with the relation expected for a BCS superconductor. We have also measured
the muon Knight shift Kμ in the normal (or paramagnetic) state of various heavy-fermion systems. Kμ is large and negative (about −1000∼−3000 ppm at T=10 K) for CeCu2Si2, UPt3 and CeAl3, while more complicated signals are measured in CePb3 and CeB6. The negative muon Knight shift in the non-magnetic heavy-fermion systems is discussed in terms of the Kondo-coupling between
the conduction- and f-electrons. 相似文献
36.
A systematic procedure which enables the study of complicated internal field distributions is discussed. It is proposed that this may be useful for studying the fields due to the flux line lattice (FLL) of the high temperature superconductors. Moment distributions of the Fourier transform of the internal field components can be obtained. We have used the London theory as developed by Kogan and others to calculate the internal field distributions, explicitly including those field components which are transverse to the average internal field. We have used this to make estimates of the expected frequency dependence of these moment distributions. 相似文献
37.
C.E. Stronach K.R. Squire A.S. Arrott B.D. Patterson B. Heinrich W.F. Lankford A.T. Fiory W.J. Kossler J.J. Singh 《Journal of magnetism and magnetic materials》1981,25(2):187-193
The temperature dependence (240 to 633 K) of the interstitial magnetic field, Bμ, as determined by the rotation of the spin of the μ+, has been measured for dilute polycrystalline iron alloys with Mo, Ti and Nb additions. In all cases the behaviours differ from one another and from the Fe(A1) alloys previously studied. Bμ, which is negative with respect to the magnetization, is increased in magnitude by A1 and Mo, and decreased greatly by Ti. The addition of Nb creates a two- phase alloy from which we can assess the role of heterogeneity and/or strain on Bμ in iron. If the temperature dependence of the hyperfine field Bhf extracted from Bμ for Fe(Mo) alloys is interpreted on the model previously used to discuss the Fe(A1) data, we would conclude that the muon is attracted to the Mo atom while repelled by the A1 atoms as the temperature decreases. Measurements giving room temperature values of Bμ for iron alloys with Mn, Cr, V and W taken after annealing above the recrystallization temperature are also reported. 相似文献
38.
W. J. Kossler H. E. Schone K. Petzinger B. Hitti J. R. Kempton E. F. W. Seymour C. E. Stronach W. F. Lankford J. J. Reilly 《Hyperfine Interactions》1986,31(1-4):235-240
Low temperature sites for muons implanted in TiHx have been found to be a mixture of interstitial and substitutional sites,
with substitutional occupancy determined by the probability that a muon in an interstitial site will have a vacant nearest
neighbor substitutional site. As with ZrHx, activation from the interstitial site is observed below 300 K. From the depolarization
rate in the substitutional site, the muon likely displaces the neighboring H atoms by about 0.1 A. Diffusion for the substitutional
muons occurs above room temperature with an activation of about 0.38 eV, which is less than the 0.505 eV for hydrogen vacancy
motion observed by NMR. To explain this the muon transition rate to a vacancy must be less than that of hydrogen. 相似文献
39.
M. R. Davis C. E. Stronach R. S. Cary W. J. Kossler X. H. Yu H. E. Schone W. F. Lankford A. R. Moodenbaugh J. Oostens P. Boolchand 《Hyperfine Interactions》1991,63(1-4):305-309
The n-type cuprate superconductor and closely related samples of the general form Nd2−x
Ce
x
CuO4−y
have been studied with the muon spin relaxation technique. Non-super-conducting samples display antiferromagnetism (AFM)
withT
N below 150 K, the value being dependent upon both Ce concentration and oxygen depletion. The results are interpreted in terms
of carrier concentration. 相似文献
40.
The first total synthesis of the polyketide apiosporic acid is presented. Key steps are a Julia-Kocienski olefination, a Suzuki-Miyaura cross-coupling, and an intramolecular Diels-Alder reaction. The absolute configuration of the natural product was determined. 相似文献