Fermi liquid state and enhanced electron correlations in the new iron pnictide CaFe$_4$As$_3$

TL;DR

The paper reports on the discovery of Fermi liquid behavior and enhanced electron correlations in CaFe4As3, highlighting magnetic ordering, resistivity drops, and specific heat characteristics indicative of strong electron interactions.

Contribution

This study provides the first detailed characterization of the electronic and magnetic properties of CaFe4As3, revealing enhanced correlations and Fermi liquid behavior in this new iron pnictide compound.

Findings

CaFe4As3 exhibits low-temperature Fermi liquid behavior.

Antiferromagnetic order occurs below 88 K, likely via SDW transition.

Resistivity drops sharply below 26.4 K, with increased susceptibility.

Abstract

The newly discovered CaFe$_4$As$_3$ system displays low-temperature Fermi liquid behavior, with enhanced electron-electron correlations. At high temperatures, the magnetic susceptibility shows Curie-Weiss behavior, with a large temperature-independent contribution. Antiferromagnetic ordering is observed below T$_N$ = (88.0 $\pm$ 1.0) K, possibly via a spin density wave (SDW) transition. A remarkably sharp drop in resistivity occurs below T$_2$ = (26.4 $\pm$ 1.0) K, correlated with a similarly abrupt increase in the susceptibility, but no visible feature in the specific heat. The electronic specific heat coefficient $\gamma$ at low temperatures is close to 0.02 J mol$^{-1}_{Fe}$ K$^{-2}$, but a higher value for $\gamma$ ($\sim$0.08 J mol$^{-1}_{Fe}$ K$^{-2}$ can be inferred from a linear C$ / $T \textit{vs.} T$^2$ just above T$_2$. The Kadowaki-Woods ratio A$/\gamma^2$ = 55$*10^{-5}$ $\mu \Omega$cm mol$^2$ K$^2 $mJ$^{-2}$ is nearly two orders of magnitude larger than that of heavy fermions.