Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (11)
Source
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Spin dynamics in the diluted antiferromagnet MnxZn1−xF2 (invited) (abstract) (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3692-3692 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The problem of spin dynamics in disordered magnets has been a subject of research for the past two decades. Diluted systems are of special interest since they exhibit percolation effects for concentrations near the percolation threshold (xp). For concentrations x〉xp the system should look uniform at long wavelengths and highly disordered at short wavelengths; the latter regime should exhibit fractal geometrical characteristics; specifically, as a function of decreasing wavelength, one might expect a crossover from magnon to "fracton'' behavior. A recent high-resolution inelastic neutron scattering study on a large (8 cm3) single crystal of (Mn0.5Zn0.5)F2 shows just these effects. At T=5 K Mn0.5Zn0.5F2 exhibits very sharp spin waves at small q and ω which become rapidly broader with increasing q; further, the excitations are essentially localized in character at higher energies. In this case by "localized'' we mean extremely broad both in energy at fixed wave vector and in wave vector at fixed energy; the crossover from "magnons'' to "fractons'' occurs when the wave vector is comparable to the inverse pair connectedness ξ−1 for the diluted system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338663
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Muon spin relaxation studies on high-TC superconductors and related antiferromagnets (invited) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6087-6091 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Muon spin rotation and relaxation (μSR) techniques have been applied to high-TC and related systems. In the antiferromagnets La2CuO4−y and YBa2Cu3O6.0–6.4, the muon precession frequency in zero field indicates that the microscopic static ordered moments do not change much despite drastic decrease of the Néel temperature with increasing oxygen content. In the family systems of the new three-dimensional superconductor (BaK)BiO3, no signature of static magnetic order was found by μSR, in sharp contrast to the two-dimensional systems with CuO planes. In the superconducting specimens La1.85Sr0.15CuO4 and YBa2Cu3O6.5–7.0, the magnetic field penetration depth λ was determined from the muon spin relaxation rate σ measured in transverse external magnetic fields. The temperature dependence of λ indicates a predominantly finite energy gap. The systematic variation of λ leads to an approximately linear relation TC∝σ∝1/λ2∝ns/m* between the transition temperature TC and the carrier density ns, which suggests a high-energy scale for the pairing interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342127
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Spatial and dynamic spin correlation of CuMn (5 at. %) spin glass: Inelastic neutron scattering study (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 3401-3403 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Neutron scattering experiments have been performed on a spin-glass CuMn (5 at. %, Tg =27.6 K). Polarized neutron measurements with coarse energy resolution show no change of instantaneous spatial spin correlation below T=60 K. Unpolarized neutron studies with fine energy resolution (ΔE=260 μeV) demonstrate that the slowing down of Mn spin fluctuations occur in the same way for all the wave vectors between 0.2 and 4.0 A(ring)−1. These results indicate that the spatial and dynamic spin correlations are completely decoupled in the spin freezing process. We also study the short-range spatial correlation of the "frozen'' spins at T=5 K using a simple model, and demonstrate the importance of the ferromagnetic coupling between the third nearest-neighbor Mn moments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Studies of static magnetic order in electron-superconductors and their parent compounds (1989)
    [s.l.] : Nature Publishing Group
    Nature 338 (1989), S. 49-51 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The technique of positive muon spin rotation2 (jxSR) has been applied extensively to the study of high- Tc superconductors and related materials3"8. In solids, the positive muon serves as a sensitive probe of the internal magnetic fields at interstitial sites(s), where the muon resides. In an ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/338049a0
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Absence of magnetic order in (Ba, K)BiO 3 (1988)
    [s.l.] : Nature Publishing Group
    Nature 335 (1988), S. 151-152 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Muon spin precession signal observed a, in a non-superconducting specimen of (Ba, K)BiO3 at T = 3.4K by applying a transverse external magnetic field Hext= 125 G, and b, in an anti-ferromagnetic YBa2Cu3C〉6 18 at T = 276 K with Hext = 100 G. The muon decay-time histogram is given as N(t) = ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/335151a0
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The effects of random fields on the critical and bicritical behavior of Mn x Zn1−x F2 (1989)
    Springer
    The European physical journal 75 (1989), S. 303-321 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have carried out a comprehensive study of the static and dynamic spin-spin correlations of Mn x Zn1−x F2 in a magnetic field. Samples withx=0.75 andx=0.5 have been studied. This system exhibits behavior closely related, if not identical, to that of the Random Field Ising Model (RFIM). An additional feature of Mn x Zn1−x F2 is that it exhibits an easily accessible bicritical point; thus one can study the changeover from the RFIM to the uniformXY model with a transverse random field. Quite generally, the instantaneous spin-spin correlations in a field are described by a combination of Lorentzian, Lorentzian-squared and delta function terms the latter corresponds to the long range order (LRO) component. In the Ising phase one finds history dependent behavior as discussed previously. In theXY phase, except very near the spin-flop boundary, one finds ergodic behavior withXY LRO and Lorentzian squared Ising fluctuations. Rather complicated instability effects are found all along the spin-flop boundary. Further, when one establishes LRO in theXY phase and lowers the field through the spin-flop value, one obtains a LRO Ising state in thex=0.75 sample whereas one obtains the field-cooled domain state in thex=0.50 sample. This dramatic difference in behavior is not understood. Our results on the RFIM aspects of the problem are consistent with our previous studies. The transition is dominated by the metastability effects with an underlying equilibrium transition which is either first order or weakly second order (β≈0). The underlying transition manifests itself directly in measurements of the dynamic response nearT N (H). From the data above the metastability boundary we deduce for the static correlation length exponentv=1.4±0.3 in good agreement with theory. We find for the RFIM crossover exponent φRF=1.5±0.2 where the errors represent the spread in values obtained from different techniques. Finally, we have determined in detail the field-temperature phase diagram of thex=0.5 sample including the critical behavior along the spin-flop line; the latter transition appears to be second order for an extended region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01321818
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    μ+ SR studies on pure MnF2 and site-diluted (Mn0.5Zn0.5)F2SR studies on pure MnF2 and site-diluted (Mn0.5Zn0.5)F2 (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 313-318 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Positive muon spin rotation and relaxation measurements have been carried out on the antiferromagnets, pure MnF2 and site-diluted (Mn0.5Zn0.5)F2, above and below the Néel temperature TN using single-crystal specimens. Two different muon signals have been found in the pure MnF2; with the precession frequency υA for the site A and υB for the site B measured in zero external magnetic field at T=5 K. We propose a picture that the signal from the A site represents the “muonium” state, and discuss the characteristic features of muonium in magnetic materials. The spin relaxation rate 1/T1, measured in zero external field, decreases rapidly with decreasing temperature below TN. The mechanism of the spin relaxation above TN is explained by the exchange fluctuations of the Mn moments, while below TN by the Raman scattering of spin waves. At the same normalized temperature T/TN, 1/T1 observed in the diluted (Mn0.5Zn0.5)F2 is significantly larger than that in the pure MnF2 below TN. The difference between the pure and diluted systems is related to the large spectral weight of low-energy magnons in (Mn0.5Zn0.5)F2 found by neutron scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401574
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Combination of muon spin relaxation and neutron scattering studies on magnetism (1989)
    Springer
    Hyperfine interactions 49 (1989), S. 205-222 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We combine the results from muon spin relaxation (μSR) and neutron scattering measurements performed on the same specimen (or system) of magnetic materials. The example on a spin glassCuMn (5%) shows that the two techniques have complementary time windows for studying dynamic spin fluctuations. In combining the results, one should note that muons and neutrons probe dynamic phenomena with different wavevectors. The results on antiferromagnetic La2CuO4−y illustrate the difference in the spatial range of static spin correlations reflected in the μSR precession frequency and the neutron Bragg peak intensity. With the examples of CeCu2.1Si2, YBa2Cu3Ox and Bi2Sr2YCu2O8+y , we point out that μSR is a superb tool for discovering static magnetic order while neutron scattering is the unique method to determine the spin structure. We emphasize that it is very fruitful to perform μSR and neutron experiments on the same specimen and to compare and combine the results for the better understanding of magnetism of various system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405142
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    μ+SR in amorphous spin glasses Pd75Fe5Si20 and Pd75Fe5P20 (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 381-387 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The zero-field muon spin relaxation functionG zz (t) has been measured as a function of reduced temperaturet=T/T g in the amorphous metallic spin glasses Pd75Fe5Si20 and Pd75Fe5P20. The results are in qualitative agreement with earlier measurements on dilute alloy spin glasses, including an onset of static order belowT g and a [t/(t-1)]2 dependence of the correlation time τc aboveT g. Both samples have the same τc (t) aboveT g and almost identical static width ΔS→Δo≃43 μS−1) asT»0, but thet-dependence of Δs nearT g differs markedly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401584
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...