Hamburg 2001 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 3: Schwere Fermionen
TT 3.6: Vortrag
Montag, 26. März 2001, 11:00–11:15, A
Investigation of the magnetic and superconducting state of CeCu2(Si1−xGex)2 single-crystals — •M. Deppe, P. Hinze, N. Oeschler, T. Tayama, C. Geibel, and F. Steglich — Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
Investigations on polycrystalline samples of CeCu2(Si1−xGex)2 shows that this system evolves continuously from a heavy-fermion-superconductor at x=0 to an antiferromagnetically ordered state, with partially Kondo compensated magnetic moments for x=1. In stoichiometric polycrystalline samples with x=0.1 the coexistence between superconductivity and magnetism is observed [1]. However, both the nature of the superconducting state and the magnetic phase are presently not settled. Though transport and magnetic measurements show evidence of magnetism for x=0.4 neutron scattering experiment could not detect the magnetic peaks [2]. This unsolved problem was our motivation to grow single-crystals of CeCu2(Si1−xGex)2 in order to investigate the magnetic structure and the superconducting order parameter in detail. The resistivity, magnetization, thermal expansion and specific heat measurements clearly disclose the presence of a second magnetic phase transition of first order type at low Ge-content, which was not observed in polycrystalline samples. The phase diagram will be discussed in connection with the interplay between superconductivity and magnetism in this system.
[1] O. Trovarelli, Phys. Rev. B 36, 1 (1997).
[2] A. Krimmel, Physica B 234-236, 877 (1997).