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TT: Fachverband Tiefe Temperaturen

TT 32: Correlated Electrons: Poster Session

TT 32.14: Poster

Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B

µSR-studies on the Heavy-Fermion-Superconductor CeCoIn₅ — •Johannes Spehling¹, Jeff Sonier², Eric Bauer³, Robert Heffner³, and Hans-Henning Klauss¹ — ¹Institut für Festkörperphysik, TU-Dresden, D-01069 Dresden, Germany — ²Department of Physics, Simon Fraser University, Burnaby, BC, Canada V5A 156 — ³Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

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 Ovchinikov in 1964/1965. We have carried out transverse field µSR-measurements between 2T and 5T (ĉ-axis parallel 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 should occur. The data clearly evidence the fielddriven change from second to first order transition at about 4.8T. On the other hand no additional line broadening is observed at very low temperatures below Tc in this orientation (ĉ || H), which disagrees with the assumption of the possible FFLO state.

[1] A. Bianchi,R. Movshovich,C. Capan,P.G. Pagliuso,and J. L. Sarrao, PRL, Vol.91, Number 18, 2003