Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 39: Correlated Electrons: Heavy Fermions 1
TT 39.10: Vortrag
Donnerstag, 26. März 2009, 12:15–12:30, HSZ 304
µSR-studies on the Heavy-Fermion-Superconductor CeCoIn5 at high magnetic fields — •Johannes Spehling1, Hans Henning Klauss1, Jeff Sonier2, Eric Bauer3, and Robert Heffner3 — 1Institut für Festkörperphysik, Technical University Dresden, D-01069 Dresden, Germany — 2Department of Physics, Simon Fraser University, Burnaby, BC, Canada — 3Los Alamos National Laboratory, Los Alamos, New Mexico 87545, U.S.A
In strong magnetic fields the Heavy Fermion superconductor CeCoIn5 shows a first order transition from the normal state into the superconducting phase [1]. It is suggested that a specifically modulated superconducting state is formed, the FFLO state, theoretically predicted by Fulde, Ferrell, Larkov and Ovchinnikov in 1964/1965 [2]. We have carried out transverse field µSR-measurements between 2T and 5T (ĉ || H) on single-crystalline CeCoIn5 in a temperature range between 25mK and 7K. In addition to the standard modulation perpendicular to the applied field due to the flux line lattice, a longitudinal modulation is expected. In that case an additional broadening of a local probe spectrum due to hyperfine fields should occur. The data clearly evidence the fielddriven change from second to first order-like transition at an external field of 4.8T. On the other hand no additional line broadening is observed at very low temperatures below Tc, which disagrees with the assumptions of a static FFLO state.
[1] A. Bianchi et al., Phys. Rev. Lett. 91, 187004 (2003).
[2] P. Fulde and R. A. Ferrell, Phys. Rev. 135, A550 (1964).