title: Evolution of c-f hybridization and two-component Hall effect in β-YbAlB4.
abstract: β-YbAlB(4) is the unique heavy fermion superconductor that exhibits unconventional quantum criticality without tuning in a strongly intermediate valence state. Despite the large coherence temperature, set by the peak of the longitudinal resistivity, our Hall effect measurements reveal that resonant skew scattering from incoherent local moments persists down to at least ~40 K, where the Hall coefficient exhibits a distinct minimum signaling another formation of coherence. The observation strongly suggests that the hybridization between f moments and conduction electrons has a two-component character with distinct Kondo or coherence scales T(K) of ~40 K and 200 K; this is confirmed by the magnetic field dependence of ρ(xy).
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan 277-8581. eoin@issp.u-tokyo.ac.jp
authors.forename: E C T
authors.initials: EC
authors.lastname: O'Farrell
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: S
authors.initials: S
authors.lastname: Nakatsuji