Volume 79, Number 1, July 2007
Article Number 17006
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 20 June 2007
EPL, 79 (2007) 17006
DOI: 10.1209/0295-5075/79/17006

Anomalous thermopower and Nernst effect in CeCoIn5: Loss of entropy current in precursor state

Y. 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 $\alpha _{xy}$ 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