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  • 1
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    Wiesbaden : Periodicals Archive Online (PAO)
    Geographische Zeitschrift. 63:2 (1975) 154 
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 101 (1995), S. 767-773 
    ISSN: 1573-7357
    Keywords: 67.50.Fi ; 43.25.+y
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Sound absorption of3He-B at 0 bar was studied at a frequency of 10 MHz. We performed pulsed experiments with different pulse lengths (4 to 15 μs) and pulse powers (0.1 to 160 μW) in the temperature range 0.2 〈 T/TC 〈 2. For pulse power less than pth ∼ 50 μW, and in the temperature range 0.4 to 0.8 Tc and zero field, the attenuation coefficient a decreases monotonically at about 0.2 cm−1 per decade of power. Above pth. α increases up to values of 3.5 cm−1 and 1.9 cm−1 at highest power for temperatures of 0.8 Tc and 0.4 Tc, respectively. At pulse power around 100 μW and at the lowest temperatures, the attenuation changes within the first 200 μs after the application of the pulse; α also increases with increasing field. In the normal fluid α decreases with increasing power. All of our observations are lacking a rigorous theoretical understanding.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 110 (1998), S. 467-472 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Novel attenuation effects and the generation of the third harmonic frequency in nonlinear zero and first sound in 3 He were found in pulsed sound-transmission experiments at various pressures (0, 10 bar), frequencies (10-50 MHz), sound-pulse energies (0.01-110 nJ) and temperatures ranging from 0.8 mK to 200 mK. The nonlinear damping of zero sound increases with the square of the frequency and demonstrates that quantum-damping exists in a Fermi liquid even for low frequency phonons at temperatures as high as 1 mK due to multiple phonon absorption processes. The origin of the additional damping found in first sound at high temperatures and sound pulse powers is unclear, but part of the apparent attenuation is caused by third harmonic generation which was also found in superfluid 3 He-B. In zero- as well as in first sound the third harmonic generation takes place in the leading edge of the propagating sound pulse at times when the fundamental frequency has not even developed to its full amplitude.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 101 (1995), S. 253-258 
    ISSN: 1573-7357
    Keywords: 76.60.−k ; 76.60.Jx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The big indirect exchange interaction and the huge nuclear magnetic moments of the two Tl-isotopes makes Tl useful at low temperatures for non linear pulsed NMR studies of inter- and intra-spin interactions mediated by the conduction electrons. We extended earlier experiments to higher fields (0.1 T 〈 Bo 〈 1 T) on a cylindrically shaped sample of 6N purity and found the proposed spin waves trapped in the skin depth of the sample which manifest themselves in line splitting with increasing tipping angles. We also found frequency shifts in partial agreement with the expectations. However, the spin susceptibility was enhanced above the paramagnetic value at temperatures below 2 mK, whereas the line width decreased by a factor of two between 5 and 1 mK. Thus, while solving the high spin-polarization puzzle of Tl (line splitting of already merged lines) we were left with two other unexplained observations.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-7357
    Keywords: 67.70.+n ; 67.80.Jd ; 75.10.J
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present measurements of the magnetization of pure3He films adsorbed on graphite at a density of p = 0.235 atoms/Å2, which corresponds to the 2D Heisenberg ferromagnetic regime. Different NMR frequencies (461.3kHz and 1.004 MHz) were used to study the magnetic field dependence of the nuclear magnetization. Measurements were performed on a Papyex sample to investigate the influence of the platelet size. The results are discussed in the context of theoretical models presented recently to describe these systems.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 108 (1997), S. 373-382 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electrical conductivity of various RuO2-based thick film paste resistors was investigated in the temperature range between 50 mK and 20K. It is shown that models based on variable range hopping and simple models based on tunnelling of charge carriers between conductive grains do not provide a satisfactory explanation for the temperature dependence of the electrical conductivity in these materials at very low temperatures. We suggest a new mechanism based on tunnelling of electrons through graded barriers between conductive particles.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 116 (1998), S. 83-89 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract NMRON studies for the $$\left. {| \pm 3} \right\rangle \to \left. {| \pm 2} \right\rangle $$ 54Mn transitions in antiferromagnetic MnBr2 $$\cdot $$ 4H2O, in the millikelvin regime, are presented and discussed. New values are given for (i) the sum of the effective molecular exchange and magnetic anisotropy fields acting on the Mn2+ ions, $$B_{\text{E}}^{{\text{eff}}} + B_{\text{A}} $$ =2.23(2) T, and (ii) the magnetic dipole hyperfine splitting, A=-201.99(1) MHz, electric quadrupole hyperfine splitting P=0.049(8) MHz and pseudoquadrupole splitting $$P\prime $$ =1.63(2) MHz for the 54Mn nuclei.
    Type of Medium: Electronic Resource
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