Regensburg 2002 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 21: Schwere Fermionen, Kondo-Systeme II (gemeinsam mit FV-Magnetismus)
TT 21.4: Vortrag
Donnerstag, 14. März 2002, 15:15–15:30, H20
Magnetically mediated superconductivity in CeTIn5? (T :Co, Rh, Ir) — •Günter Sparn1, Robert Borth1, Edit Lengyel1, John Sarrao2, Frank Steglich1, and Joe D. Thompson2 — 1MPI Chemical Physics of Solids, Nöthnitzerstr. 40, 01187 Dresden — 2Los Alamos National Laboratory, Los Alamos, New Mexico 87545, U.S.A.
For an increasing number of heavy-fermion (HF) compounds superconductivity (SC) is found close to a magnetic instability (quantum critical point: QCP). In a working hypothesis, this is taken as evidence for the realization of a non-phononic pairing mechanism. Unfortunately, a detailed study of the interplay between magnetism and superconductivity up to now was hampered by the extreme conditions of temperature and/or pressure needed to reach the QCP. This situation improved significantly after the discovery of CeTIn5, a new class of HF compounds based on the HF antiferromagnet (AFM) CeIn3. Reminiscent to CeIn3 superconductivity at Tc ≈ 2 K is found in the AFM CeRhIn5 at a critical pressure of pc = 1.6 GPa at which AFM order vanishes. CeCoIn5 exhibits a record high value of Tc = 2.3 K (among HF superconductors) and no long range magnetic order already at ambient pressure. Here we report on heat capacity measurements under hydrostatic pressure of Ce(Rh1−xIrx)In5 (pmax = 1.8 GPa) and CeCoIn5 (pmax = 3 GPa) and discuss the results in light of current theories of unconventional superconductivity.