A novel non-Fermi-liquid state in the iron-pnictide FeCrAs

TL;DR

This paper investigates the unusual non-Fermi-liquid behavior of FeCrAs, revealing a persistent non-metallic resistivity and a novel low-temperature state distinct from conventional Fermi liquids.

Contribution

It reports the discovery of a new non-Fermi-liquid state in FeCrAs characterized by unique transport and thermodynamic properties.

Findings

Resistivity increases with decreasing temperature over a wide range.

Resistivity follows a non-Fermi-liquid power law below 10 K.

Specific heat exhibits Fermi-liquid behavior with a large Sommerfeld coefficient.

Abstract

We report transport and thermodynamic properties of stoichiometric single crystals of the hexagonal iron-pnictide FeCrAs. The in-plane resistivity shows an unusual "non-metallic" dependence on temperature T, rising continuously with decreasing T from ~ 800 K to below 100 mK. The c-axis resistivity is similar, except for a sharp drop upon entry into an antiferromagnetic state at T_N 125 K. Below 10 K the resistivity follows a non-Fermi-liquid power law, rho(T) = rho_0 - AT^x with x<1, while the specific heat shows Fermi liquid behaviour with a large Sommerfeld coefficient, gamma ~ 30 mJ/mol K^2. The high temperature properties are reminiscent of those of the parent compounds of the new layered iron-pnictide superconductors, however the T -> 0 properties suggest a new class of non-Fermi liquid.