Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 7: Korrelierte Elektronen: Schwere Fermionen

TT 7.8: Vortrag

Montag, 8. März 2004, 16:30–16:45, H19

Investigation of the magnetic and the superconducting states of CeCu₂Si₂ using large single crystal. — •H.S. Jeevan¹, M. Deppe¹, O. Stockert¹, R. Borth¹, E. Faulhaber², C. Geibel¹, and F. Steglich¹ — ¹Max Planck Institute for Chemical Physics of Solids, Dresden — ²TU Dresden, IAPD, D-01062 Dresden, Germany.

The discovery of superconductivity in CeCu₂Si₂ in 1979 opened the field of unconventional superconductivity in strongly correlated systems. Later on, another unconventional phase, the A-phase, of presumably magnetic character was found to compete with the superconducting phase in CeCu₂Si₂. Despite more than 20 years of intensive research, the nature of the superconducting phase and of the A-phase as well as the interaction between both are very far from being understood. A major problem is the lack of large single crystals with well defined physical properties. This prevents e.g. a study of the magnetic structure and magnetic excitations of this compound with neutron scattering, which would allow a much deeper insight into the nature of these unconventional phases. We have developed a self-flux growth method, which allows the growth of large CeCu₂Si₂ single crystal with well defined properties. The ground state can be tuned by changing growth parameters. We have investigated the magnetic and the superconducting ground state using specific heat, resistivity and susceptibility measurements. The preliminary neutron scattering measurements allow us to determine for the first time the magnetic structure of the A-phase. We shall analyse and discuss the physical properties of these single crystals and their relation to growth parameters.