Evolution of c-f hybridization and two component Hall effect in \beta-YbAlB_4

TL;DR

This paper investigates the complex hybridization and Hall effect behavior in -YbAlB_4, revealing a two-component hybridization process with distinct coherence scales, contributing to understanding unconventional quantum criticality in heavy fermion systems.

Contribution

It uncovers a two-component hybridization mechanism with separate Kondo scales in -YbAlB_4, advancing knowledge of quantum criticality in heavy fermion superconductors.

Findings

Resonant skew scattering persists down to ~40 K.

Hall coefficient shows a minimum at ~40 K indicating coherence formation.

Magnetic field dependence confirms two distinct Kondo or coherence scales.

Abstract

\beta-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 \rho_xy.