UC Irvine

The Hall effect is found to set the scale for coherence in the normal state of CeCu6 and U2PtC2. CeCu6 is a nonmagnetic, nonsuperconducting heavy fermion system.1–4 Its resistivity at high temperature is like that of a collection of incoherent Kondo scatterers. At low temperature the resistivity smoothly decreases to a very small value, indicating that scattering has become coherent. The Hall effect has two strong extrema in its temperature dependence which define a high-temperature incoherent scattering region, a transition region, and a low temperature coherent region. Although U2PtC2 is superconducting below 1.5 K,5 the Hall results in the normal state show two extrema similar to those of CeCu6. However, these features are scaled to higher temperatures, consistent with the smaller low-temperature electronic specific heat and higher Fermi temperature.