Quasi-linear `non-metallic' resistivity in the distorted-kagome metal CrPdAs

TL;DR

This study reports on the growth, characterization, and unusual resistivity behavior of CrPdAs, a distorted-kagome metal with spin-glass properties, Dirac band crossings, and non-metallic resistivity across a broad temperature range.

Contribution

It presents the synthesis of single-phase CrPdAs crystals with controlled disorder and reveals its unique quasi-linear, non-saturating resistivity from 300 K to 2 K, unlike typical metallic behavior.

Findings

CrPdAs exhibits spin-glass behavior around 60 K.

CrPdAs shows a large linear heat capacity coefficient, typical of kagome metals.

CrPdAs displays a quasi-linear, non-metallic resistivity from 300 K down to 2 K.

Abstract

We report the growth and characterization of single crystals of the disorted-kagome lattice compound CrPdAs. Spin-glass behaviour with $T_{SG} \sim 60\ {\rm K}$ is observed in all crystals tested. Some growths show in addition a magnetic impurity phase with $T_c$ around 200 K, but annealing produces single-phase crystals without the ferromagnetic impurity phase. Single-phase crystals nevertheless have $29\pm 5\%$ anti-site disorder of the Cr and Pd sites, similar to a previous generation of flux-grown polycrystalline samples. We observe a large linear-coefficient of the heat capacity at low temperature, $\gamma = 23 \pm 3$ mJ/mole\,K$^2$, which is typical of kagome metals. The calculated band structure shows several Dirac band-crossings very near $E_F$ whose degeneracy is lifted when spin-orbit interaction is included. Our most curious finding is a `non-metallic' in-plane resistivity, extending over the entire measured temperature range from 300 K down to 2 K. This resistivity is quasi-linear below about 130 K, and shows no sign of saturation down to the lowest temperature measured.