Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Postersession Correlated Electrons: (General) Theory, Low-Dimensional Systems, Kondo Physics, Heavy Fermions, Quantum-Critical Phenomena
TT 6.55: Poster
Montag, 23. März 2009, 13:00–16:45, P1A
Low-temperature specific heat of the heavy-fermion superconductor CeCu2Si2 — •Julia Arndt1, Oliver Stockert1, Robert Borth1, Thomas Lühmann1, Hirale Jeevan1,2, Christoph Geibel1, Michael Loewenhaupt3, and Frank Steglich1 — 1Max-Planck-Institut f. Chem. Physik fester Stoffe, Dresden — 2I. Physikal. Inst., U Göttingen — 3Inst. f. Festkörperphysik, TU Dresden
CeCu2Si2, the first heavy-fermion superconductor to be discovered, exhibits a complex interplay of antiferromagnetism and superconductivity (SC). In very subtle dependence on the exact stoichiometry its ground state is either antiferromagnetically ordered (A-type), superconducting (S-type), or both (A/S-type). Recent neutron scattering experiments on S-type CeCu2Si2 (Tc≈ 600 mK) [1] and their theoretical interpretation [2] give indications of magnetically mediated SC with an order parameter of dx2−y2 symmetry. Different order parameter symmetries cause characteristic temperature dependences of the specific heat well below Tc. We performed measurements of the specific heat at temperatures from 50 mK to 4 K and magnetic fields up to 8 T on large single crystals of A-, S- and A/S-type CeCu2Si2 as well as on 2% and 10% Ge doped CeCu2Si2 using an adapted quasi-adiabatic heat-pulse method with background heating. The results are compared with each other, with special focus given to the analysis of the low-temperature specific heat of S-type CeCu2Si2 in order to be able to draw conclusions as to the nature of SC in the system.
[1] O. Stockert et al., Physica B 403, 973 (2008)
[2] I. Eremin et al., Phys. Rev. Lett. 101, 187001 (2008)