Semimetallic Kondo lattice behavior in YbPdAs with a distorted kagome structure

TL;DR

YbPdAs exhibits semimetallic Kondo lattice behavior with a distorted kagome structure, showing antiferromagnetic order, low carrier concentration, and a crossover from single-ion to coherent Kondo effects at low temperatures.

Contribution

This study reports the synthesis and characterization of YbPdAs with a distorted kagome lattice, revealing its low-carrier Kondo lattice behavior and magnetic properties.

Findings

Antiferromagnetic transition at 6.6 K with partial magnetic entropy recovery.

Resistivity shows -ln T dependence and a maximum at 12 K indicating Kondo coherence.

Low carrier concentration evidenced by Hall measurements and band calculations.

Abstract

We have synthesized YbPdAs with the hexagonal ZrNiAl-type structure, in which the Yb-atoms form a distorted kagome sublattice in the hexagonal basal plane. Magnetic, transport, and thermodynamic measurements indicate that YbPdAs is a low-carrier Kondo lattice compound with an antiferromagnetic transition at $T_\mathrm{N}$ = 6.6 K, which is slightly suppressed in applied magnetic fields up to 9 T. The magnetic entropy at $T_\mathrm{N}$ recovers only 33\% of $R\ln{2}$, the full entropy of the ground state doublet of the Yb-ions. The resistivity displays a $-\ln T$ dependence between 30 and 15 K, followed by a broad maximum at $T\rm_{coh}$ = 12 K upon cooling. Below $T\rm_{coh}$, the magnetoresistance changes from negative to positive, suggesting a crossover from single-ion Kondo scattering processes at intermediate temperatures to coherent Kondo lattice behaviors at low temperatures. Both the Hall resistivity measurements and band structure calculations indicate a relatively low carrier concentration in YbPdAs. Our results suggest that YbPdAs could provide an opportunity for examining the interplay of Kondo physics and magnetic frustration in low carrier systems.