Field dependent effective masses in YbAl$_{3}$

TL;DR

This study reveals that in YbAl₃, high magnetic fields reduce effective electron masses, indicating a link between magnetic field effects and the suppression of Fermi liquid anomalies rather than 4f electron polarization.

Contribution

It demonstrates that the effective mass reduction at high fields in YbAl₃ is associated with the removal of Fermi liquid anomalies, not 4f polarization, providing new insight into field effects in intermediate valence compounds.

Findings

High field effective masses are about half of low field masses.

The critical field B* is much smaller than the Kondo field B_K.

B* is comparable to the field associated with Fermi liquid coherence temperature.

Abstract

We show for the intermediate valence compound YbAl$_{3}$ that the high field (40 $\lesssim B \lesssim$ 60T) effective masses measured by the de Haas-van Alphen experiment for field along the $<111>$ direction are smaller by approximately a factor of two than the low field masses. The field $B^{*} \sim$ 40T for this reduction is much smaller than the Kondo field $B_{K} \sim k_{B}T_{K}/\mu_{B}$ ($T_{K}\sim$ 670K) but is comparable to the field $k_{B}T_{coh}/\mu_{B}$ where $T_{coh}\sim$ 40K is the temperature for the onset of Fermi liquid coherence. This suggests that the field scale $B^{*}$ does not arise from 4$f$ polarization but is connected with the removal of the anomalies that are known to occur in the Fermi liquid state of this compound.