High pressure transport studies of the LiFeAs analogs CuFeTe2 and Fe2As

We have synthesized two iron-pnictide/chalcogenide materials, CuFeTe2 and Fe2As, which share crystallographic features with known iron-based superconductors, and carried out high pressure electrical resistivity measurements on these materials to pressures in excess of 30 GPa. Both compounds crystallize in the Cu2Sb-type crystal structure that is characteristic of LiFeAs (with CuFeTe2 exhibiting a disordered variant). At ambient pressure, CuFeTe2 is a semiconductor and has been suggested to exhibit a spin-density-wave transition, while Fe2As is a metallic antiferromagnet. The electrical resistivity of CuFeTe2, measured at 4 K, decreases by almost two orders of magnitude between ambient pressure and 2.4 GPa. At 34 GPa, the electrical resistivity decreases upon cooling the sample below 150 K, suggesting the proximity of the compound to a metal–insulator transition. Neither CuFeTe2 nor Fe2As superconduct above 1.1 K throughout the measured pressure range. (paper)