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

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 similar to 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 similar to 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 similar to 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 K properties suggest a new class of non-Fermi liquid. Copyright (C) EPLA, 2009