UC Irvine

YbAl3 is an intermediate valent compound with a large Kondo temperature T-K and moderately low conduction electron density. Because of this, YbAl3 is a prime candidate for the observation of effects caused by low conduction electron density, where coherence sets in below T-coh rather than T-K (T-coh much less than T-K). For the first time, we have directly observed the cross over between the energy scales by the application of a magnetic field above B* approximate to 40 T (approximate to k(B)T(coh)/mu(B)). We also observe a reduction in the effective masses above B* that is consistent with the energy scale crossover.