Paglione Johnpierre, Tanatar M A, Hawthorn D G, Ronning F, Hill R W, Sutherland M, Taillefer Louis, Petrovic C
Department of Physics, University of Toronto, Toronto M5S 1A7, Canada.
Phys Rev Lett. 2006 Sep 8;97(10):106606. doi: 10.1103/PhysRevLett.97.106606.
Heat and charge transport were used to probe the magnetic field-tuned quantum critical point in the heavy-fermion metal CeCoIn5. A comparison of electrical and thermal resistivities reveals three characteristic energy scales. A Fermi-liquid regime is observed below T(FL), with both transport coefficients diverging in parallel and T(FL) -->0 as H --> Hc, the critical field. The characteristic temperature of antiferromagnetic spin fluctuations, T(SF), is tuned to a minimum but finite value at Hc, which coincides with the end of the T-linear regime in the electrical resistivity. A third temperature scale, T(QP), signals the formation of quasiparticles, as fermions of charge e obeying the Wiedemann-Franz law. Unlike T(FL), it remains finite at Hc, so that the integrity of quasiparticles is preserved, even though the standard signature of Fermi-liquid theory fails.
