The Lorenz number in CeCoIn5 inferred from the thermal and charge Hall currentsY. Onose1, N. P. Ong1 and C. Petrovic2
1 Department of Physics, Princeton University - Princeton, NJ 08544, USA
2 Department of Physics, Brookhaven National Laboratory - Upton, NY 11973, USA
received 25 June 2007; accepted in final form 5 September 2007; published November 2007
published online 28 September 2007
The thermal Hall conductivity and Hall conductivity in CeCoIn5 are used to determine the Lorenz number at low temperature T. This enables the separation of the observed thermal conductivity into its electronic and non-electronic parts. We uncover evidence for a charge-neutral, field-dependent thermal conductivity, which we identify with spin excitations. At low T, these excitations dominate the scattering of charge carriers. We show that suppression of the spin excitations in high fields leads to a steep enhancement of the electron mean-free-path, which leads to an interesting scaling relation between the magnetoresistance, thermal conductivity and .
71.27.+a - Strongly correlated electron systems; heavy fermions.
72.15.Eb - Electrical and thermal conduction in crystalline metals and alloys.
72.20.My - Galvanomagnetic and other magnetotransport effects.
© Europhysics Letters Association 2007