Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 3: Correlated Electrons: Quantum-Critical Phenomena
TT 3.2: Vortrag
Montag, 27. März 2006, 09:45–10:00, HSZ 301
Hidden Quantum Critical Point in CeCoIn5−xSnx Studied by Thermal Expansion and Grüneisen Ratio Divergence — •G. Donath1, R. Küchler1, P. Gegenwart1, E.D. Bauer2, J.L. Sarrao2, and F. Steglich1 — 1Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany — 2Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 USA
The heavy fermion superconductor CeCoIn5−xSnx has attracted much interest because of a magnetic field-induced quantum critical point at HQCP that coincides with the upper critical field Hc2 for unconventional superconductivity. Most remarkably, it is not possible to separate both phenomena from each other. By contrast, HQCP is pinned to Hc2 if superconductivity is weakened by Sn substitution [1].
We present low-temperature thermal expansion measurements, α(T,B), for the various concentrations, x=0, 0.03, 0.06, 0.09, 0.12, 0.18, and compare them with the predictions of the spin-density-wave theory for an antiferromagnetic quantum critical point.
Furthermore, the effect of Sn subsitution on the Grüneisen ratio Γ(T)∝α/C (C: specific heat) is discussed.
[1] E.D. Bauer et al., Phys. Rev. Lett. 94, 047001 (2005)