Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 26: CE: Heavy Fermions

TT 26.6: Vortrag

Mittwoch, 24. März 2010, 15:30–15:45, H21

Field-induced coupled superconductivity and spin density wave order in the heavy fermion compound CeCoIn₅ — •Johannes Spehling¹, Hans-Henning Klauss¹, Robert Heffner², Eric Bauer², Jeff Sonier³, and Nicholas Curro⁴ — ¹Institut für Festkörperphysik, TU Dresden, Germany — ²Los Alamos National Laboratory, Los Alamos, New Mexico , U.S.A. — ³Department of Physics, Simon Fraser University, Burnaby, Canada — ⁴Department of Physics, UC Davis, California, U.S.A

In strong magnetic fields the Heavy Fermion superconductor CeCoIn₅ shows a first order transition from the normal state into the SC phase [1]. Several modulated SC phases are suggested at high magnetic fields in CeCoIn₅, e.g., the spin singlet FFLO [2] and mixed singlet/triplet phases (Q-phase) [3]. We have carried out transverse field muSR measurements between 2 T and 5 T (H parallel c-axis) on single crystalline CeCoIn₅ in a temperature range between 25 mK and 7 K. In addition to the standard modulation perpendicular to the applied field due to the vortex lattice, a longitudinal modulation is expected. For the modulated high field phases in a local probe experiment an additional line or a static line broadening should occur. Our data clearly evidence the fielddriven change from second to first order transition at an applied field of 4.8 T. Temperature and field dependence of the muon spin relaxation rate support the formation of a mode-coupled SC and AFM ordered phase in CeCoIn₅ for fields directed parallel to the c-axis.

[1] A. Bianchi et al., PRL 91, 187004 (2003).

[2] P. Fulde and R.A. Ferrell, Phys. Rev. 135, A550 (1964).

[3] A. Aperis et al., arXiv:0902.0553.