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  • 11
    Electronic Resource
    Electronic Resource
    Myoniumchemie in der Gasphase (1978)
    Springer
    Colloid & polymer science 256 (1978), S. 705-705 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01784432
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  • 12
    Electronic Resource
    Electronic Resource
    Quantum Diffusion in Cryocrystals Studied by Muon Spin Relaxation (1998)
    Springer
    Journal of low temperature physics 111 (1998), S. 303-319 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We review our recent studies of muonium diffusion in cryocrystals. Atomic muonium (Mu = μ + e − ) may be considered as a light isotope of hydrogen and so provides the prototypical light interstitial defect in these sytems, themselves the simplest of insulators. Experiments using the muon spin relaxation techniques in transverse and longitudinal (zero) magnetic fields reveal tunneling motion at low temperatures, governed by various mechanisms of phonon scattering. The results are compared with the current theories of quantum diffusion in insulators. A two–phonon scattering mechanism is found to dominate at low temperatures in solid nitrogen, methanes and carbon dioxide, whereas a one–phonon interaction provides the main channel at temperatures comparable to the Debye temperature in solid nitrogen, xenon and krypton. Particular attention is devoted to quantum diffusion processes in the presence of static crystal disorder. At low temperatures, the muonium diffusion can no longer be described in terms of a single correlation time. The localization and delocalization effects in the Mu diffusion in such inhomogeneous crystals are discussed in detail. Finally, the authors give an analysis of trapping phenomena for muonium in insulators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022275317457
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  • 13
    Electronic Resource
    Electronic Resource
    Positive muons in antimony bismuth alloys (1984)
    Springer
    Hyperfine interactions 17 (1984), S. 387-391 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract StroboscopicμSR and TD-μSR techniques were used to measure theμ + Knight shiftK μ, and relaxation rateλ inSbBi alloys as functions of magnetic fieldH, temperatureT, the angleθ betweenH and the crystallineĉ axis, and the concentration [Bi] of alloyed Bi. In pure Sb and inSbBi (6.5%),K μ (θ=0) andK μ (θ=π/2) both decrease linearly withT up to about 100 K, but bothK μ and its anisotropy are smaller in the 6.5% alloy, indicating a “dilution” effect. With 15 at % Bi,K μ is reduced further but itsT-dependence and that ofλ are dramatically altered. At low temperaturesK μ (θ=0) inSbBi(15%) actually becomes negative and the sign of the anisotropy is reversed. In the same sample,λ is proportional toH at both 20 K and 150 K; at 120 Kλ is proportional toK μ ifθ is used as an implicit variable, but at 36 K this is not the case. A consistent phenomenological description is offered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02065931
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  • 14
    Electronic Resource
    Electronic Resource
    Muonium formation in diamond and oxide insulators (1984)
    Springer
    Hyperfine interactions 18 (1984), S. 567-573 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In order to provide a larger data base for understanding the whys and why nots of muonium formation in solids, we have been searching for Mu in predominantly crystalline environments. We have observed muonium in room temperature diamond, and report on a brief study of the temperature behaviour of its asymmetry and relaxation. These results are radically different from all previous diamond results. We have not been able to detect any Mu in SrTiO3, ZrSiO4, or TiO2, but in GeO2 there is a tiny signal in both a fused sample and a hexagonal single crystal, but none in a tetragonal crystal. Since hexagonal GeO2 is structurally similar to quartz, one would naively expect similar amounts of Mu. Such is not the case, the reasons for which are not understood at this time. In SrTiO3, the muon asymmetry is a strong function of temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02064869
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  • 15
    Electronic Resource
    Electronic Resource
    Diffusion, trapping and detrapping of positive muon in Al-0.047% Mg (1984)
    Springer
    Hyperfine interactions 17 (1984), S. 211-217 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Positive muon spin relaxation was measured in Al-0.047% Mg quenched from 873 K under zero external magnetic field from 6.3 K to 270 K. The observed spectra were analysed with the calculated muon spin relaxation function which included the static relaxation rates, the trapping rates, the detrapping rates and thet=0 initial trapping fractions. Due to the precise measurements and the realistic expression of spin relaxation function, above four parameters could be determined distinctly. The trapping rates and the distortions around a muon were determined from the values of static relaxation rates at a trapping site. The diffusion features were clearly described by the trapping and detrapping rates. The diffusion process was determined by the temperature dependence of these parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02065904
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  • 16
    Electronic Resource
    Electronic Resource
    Muon spin relaxation in CeCu2Si2 and muon knight shift in various heavy-fermion systems (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 413-418 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401589
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  • 17
    Electronic Resource
    Electronic Resource
    μ+knight shifts and trapping in diluteSbSn alloys (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 433-437 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Giant μ+ Knight shifts Kμ have been studied previously in Sb andSbBi alloys. Here we report μ+SR measurements on Sb with dilute heterovalent Sn impurities. A dramatic concentration dependence is observed: Kμ is increased slightly (relative to the value in pure Sb) by Sn concentrations of 〈0.1%, whereas larger concentrations cause a drastic reduction of Kμ. One concern could be that Kμ values in the alloy might reflect local band structure in trap sites near Sn impurities rather than the bulk “host” band structure of the alloy. This is indeed the case in bothSbSn (0.03%) andSbSn (0.06%), where a second, lower frequency TF-μSR signal begins to appear for T〉60K. The amplitude of the low Kμ signal grows with increasing T at the expense of the amplitude of the high-Kμ, low-T signal, suggesting that the μ+ migrates through the host lattice to trap sites. A simple trapping model correctly describes the observed T-dependence of the amplitudes, phases and relaxation rates of the two signals. We conclude that the low-T Knight shift is truly characteristic of the host band structure while the much lower Kμ value of the high-T site is characteristic of a specific trap site, presumably adjacent to a Sn impurity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401592
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  • 18
    Electronic Resource
    Electronic Resource
    Spin dynamics in crystalline and amorphous DyAg (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 303-308 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Crystalline (cr-) Dyag [CsC] structure] orders antiferro-magnetically with TN≅60K; amorphous (am-) DyAg ferro-magnetically with TC≈-18K. We measured the longitudinal field (LF) μ+SR relaxation functions GZZ(t) for 5K〈T〈300K using surface muons. In the paramagnetic state. cr-DyAg gives an exponential GZZ (t) in the relaxation rate rising first slowly then more rapidlynear TN; no decoupling is observed in LF up to 0.4T. In the ordered state we see a Lorentzian Kubo-Toyabe GZZ(t), becoming nearly static at the lowest temperatures. Its static width is very narrow (Δ≈-7 MHz), and full dceoupling is achieved here in 0.1 T. On approaching TN, the fluctuation rate and the static width increase mootonically bt the field distribution remains Loratzian. A LF of 0.4T is then insufficient to quench the fast exponential relaxation. In paramagnetic am-DyAg, the μ+ depolarization is always much faster then in cr-DyAg. At lower temperatures it is better described by a root-exponential than an exponential GZZ(t). Below TC an exponentially relaxing signal with 1/3 amplitude is seen. The decoupling effect of LF up to 0.4T was negligible at all temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401572
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  • 19
    Electronic Resource
    Electronic Resource
    Thermal hopping ofμ + between “FμF” centres in NaF (1986)
    Springer
    Hyperfine interactions 32 (1986), S. 677-682 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Strongly hydrogen-bonded diamagnetic “FμF” centres are formed by theμ + in a wide variety of fluoride crystals. Hydrogen atoms are expected to form similar “FHF” complexes. Through the “motional narrowing” of the zero-field muon relaxation function in NaF, we have observed an Arrhenius temperature dependence of the dissociation rate of theFμF complex, yielding a binding energy of 1700 (200) K for theμ + in theFμF centre.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02394972
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  • 20
    Electronic Resource
    Electronic Resource
    Temperature dependence of the μ+ hyperfine field in Gd and Co and its comparison with other ferromagnets (1978)
    Springer
    Hyperfine interactions 4 (1978), S. 318-322 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01021843
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