Dresden 2003 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 14: Postersitzung III (Neue u. unkonventionelle Supraleiter, Anwendungen der Supraleitung, Dünne Schichten, JJs und SQUIDs, Schwere Fermionen, Kondo-Systeme)
TT 14.37: Poster
Mittwoch, 26. März 2003, 14:30–19:00, P2c
Specific heat measurements at low temperatures using a compensated quasi-adiabatic heat-pulse method — •Teodora Rus, Thomas Lühmann, Heribert Wilhelm, and Frank Steglich — Max–Planck–Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden
We developed a compensated quasi-adiabatic heat-pulse method for heat
capacity measurements at low temperatures. The system is capable of
measuring the specific heat of very small samples (m≈5−30 mg)
in the temperature range 0.03 K < T < 6 K and for magnetic fields B
<12 T. To check the performance of the new set-up the specific heat
of CeCu2Si2, a heavy-fermion superconductor, was measured for
0≤ B≤ 8 T. The obtained C(T) data are in perfect
agreement with published data. Furthermore, we will present C(T)
results on a single crystal of
YbRh2(Si0.95Ge0.05)2. This system is close to the
magnetic/non-magnetic borderline, indicated by an antiferromagnetic
ordering temperature as low as TN = 0.02 K [1]. Above T≈
0.3 K, C(T) is almost identical to the data reported for
YbRh2Si2 [2], where the electronic specific Cel/T heat
shows a logarithmic divergence up to 10 K. At lower temperatures,
however, Cel/T exhibits a pronounced deviation from this
logarithmic temperature dependence. For magnetic fields B> 1 T,
Cel/T is field independent, in agreement with the
Landau-Fermi-liquid picture. The field dependence of Cel/T and
further details will be presented.
[1] J. Custers et al., to be published.
[2] P. Gegenwart et al., Phys. Rev. Lett. 89, 056402 (2002).