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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3589-3592 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The measurements of x-ray diffraction, the temperature dependence of the dc resistance and the ac susceptibility have been performed for the single-phase 3D-metal doping systems YBa2 Cu3−x Mx Oy (M=Fe, Co, and Ni; x=0.025, 0.05, 0.075, 0.10, 0.25, and 0.50 for Ni and Co and 0.05, 0.075, 0.10, 0.15, and 0.20 for Fe). With an increase of impurity content, two structural transitions were observed for the Co and Fe dopants but only one for the Ni dopant. The resistivity in the normal state changes from metallic to semiconductinglike behavior and the depression of Tc is linear with the impurity concentration (x) when x〈0.10. A weak Curie–Weiss type paramagnetism, which is enhanced with impurity content, exists in the samples studied. Incorporating other work on oxygen defects, we suggest that a change of oxygen content induced by doping was the dominant effect on superconductivity in these samples.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 100 (1995), S. 167-171 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract For temperatures above the solid ordering temperature TN=0.934 mK, the molar volumes v1 and vs of liquid and solid3He at melting pressure, Pm are determined primarily by the melting pressure and the compressibility. However, in the vicinity of TN and below, vs(T) is influenced greatly by the expansion coefficient, which becomes large and negative. Using existing thermodynamic data, we find that vs(T) has a minimum at TN with a negative slope for T 〈 TN. A constant-volume, all-solid sample starting at T=0 with the pressure just above Pm would begin to melt as TN is approached, becoming all-solid again somewhat above TN.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 121 (2000), S. 701-706 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Simultaneous measurements of pressure and magnetic susceptibility have been made in 3 He nano-clusters embedded in a 4 He matrix, following phase separation of the mixture. Susceptibility measurements extend from 0.5 mK to 10 mK for three different samples, which either undergo partial melting upon further cooling, or separate with liquid already present. The magnetic behavior of the clusters indicates solid fractions of 77, 54, and 19%, respectively, for pressures of 3.36 MPa, 3.06 MPa, and 2.88 MPa. The susceptibility of the 3.36 MPa sample follows a Curie law to the lowest temperature. For 3.06 MPa, we observe a kink in χ at 1.1 mK, which is approximately the ordering temperature TN of the pure bulk 3 He if it existed at this pressure. However χ is almost constant down to 0.6 mK, with no drop at 1.1 mK, and no frequency shift, within our resolution of ∼10 Hz. Thus if there is magnetic ordering at 1.1 mK it is quite different than for bulk 3 He, not the U2D2 phase. For 2.88 MPa, χ follows a Curie-Weiss law with a positive Weiss θ=140 μK, indicative of a ferromagnetic tendency, similar to that seen in 2D films.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 101 (1995), S. 305-310 
    ISSN: 1573-7357
    Keywords: 64.70.D ; 67.80 ; 07.20.D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract High-precision measurements of the3He melting pressure versus temperature have been made from 500 μK to 25 mK using a60Co nuclear orientation primary thermometer and a Pt NMR susceptibility secondary thermometer. Temperatures for the fixed points on the melting curve are: the superfluid A transition TA = 2.505 mK, the A-B transition TAB = 1.948 mK, and the solid ordering temperature tn = 0.934 mK. These fixed points and a functional form for P(T) constitute a convenient temperature scale, based on a primary thermometer, usable to well below 1 mK.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 89 (1992), S. 355-364 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New measurements of the melting pressure of solid3He Pm(T,B) have been made through the paramagnetic phase-to-high field phase transition. Temperatures were determined with Pt NMR and the3He melting pressure in zero field measured in a second cell. In a field of 0.405 T, we find a change in entropy through the HFP-PP transition of ΔS/Rln2=0.13 over a temperature interval of only about 4 µK. Thus, we conclude that the transition is first-order at low fields. The entropy discontinuity decreases with field and the transition region broadens, with the transition possibly becoming second-order above a tricritical point near 0.6 T.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The temperature dependent magnetic susceptibility, χ(T), of two samples of the S=1 linear-chain Heisenberg antiferromagnet Ni(C2H8N2)2NO2(ClO4), known as NENP, has been measured from 400 K to 264 µK. Our measurements are in agreement with existing results of other researchers who worked above 1.2 K. Below 1.2 K, χ(T) increases with decreasing temperature. The results suggest that this increase is intrinsic to the NENP and is not a consequence of a single source of paramagnetic impurities in the samples.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 89 (1992), S. 715-718 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report measurements of the asymmetry of the intensities of the quadrupolar fine structure of NMR lines in ferromagnetic MnSb down to 30 mK. The asymmetry ratios provide a means of measuring the temperature, and is an example of the use of population difference thermometry as a primary thermometer for ultra-low temperatures.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two nuclear-demagnetization cryostats, each containing 173 mol of copper coolant in a 8 T magnetic field and based on an Oxford Instruments model 1000 dilution refrigerator, have been under development at the University of Florida Microkelvin Laboratory for studies of nuclear magnetic ordering in metals and in solid3He, properties of superfluid3He at T≈0, and mesoscopic systems, and for development of primary thermometers based on population differences in nuclear quadrupole systems. The performance of the first cryostat is analyzed with emphasis on improvements to be made.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 99 (1995), S. 167-182 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using60Co γ-ray anisotropy radiation as a primary thermometer, with a Pt NMR susceptibility secondary thermometer, we have made high-precision measurements of the3He melting pressure versus temperature from 500 μK to 25 mK. Temperatures obtained for the fixed points on the melting curve are: the superfluid A transition TA = 2.505mK, the A-B transition TAB = 1.948 mK, and the solid ordering temperature TN = 0.934 mK. We provide a functional form for P(T), which, with the fixed points, constitutes a convenient temperature scale, based on a primary thermometer, usable to well below 1 mK.
    Type of Medium: Electronic Resource
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