Anomalous thermopower and Nernst effect in CeCoIn5: Loss of entropy current in precursor stateY. Onose1, Lu Li1, C. Petrovic2 and N. P. Ong1
1 Department of Physics, Princeton University - Princeton, NJ 08544, USA
2 Department of Physics, Brookhaven National Laboratory - Upton, NY 11973, USA
received 8 May 2007; accepted in final form 30 May 2007; published July 2007
published online 20 June 2007
The heavy-electron superconductor CeCoIn5 exhibits a puzzling precursor state above its superconducting critical temperature at Tc = 2.3 K. The thermopower and Nernst signal are anomalous. Below 15 K, the entropy current of the electrons undergoes a steep decrease reaching ~0 at Tc. Concurrently, the off-diagonal thermoelectric current is enhanced. The delicate sensitivity of the zero-entropy state to field implies phase coherence over large distances. The prominent anomalies in the thermoelectric current contrast with the relatively weak effects in the resistivity and magnetization.
71.27.+a - Strongly correlated electron systems; heavy fermions.
72.15.Eb - Electrical and thermal conduction in crystalline metals and alloys.
74.70.Tx - Heavy-fermion superconductors.
© Europhysics Letters Association 2007