CuFeAs: A New Member in the 111-Family of Iron-Pnictides

We have synthesized CuFeAs, a new iron-pnictide compound with a layered tetragonal Cu2Sb type structure [space group P4/nmm: a = b = 3.7442(2) A and c = 5.8925(4) A] that is identical to that of 111-type iron-based superconductors. Our measurements suggest that in low applied magnetic field it undergoes an antiferromagnetic transition below TN ∼ 9 K. When compared with the ground state of CuFeSb, recently reported 111-type ferromagnetic material (TC ∼ 375 K), it has important implication with regard to the nature of Fe–Fe magnetic interaction in Fe–As materials. CuFeAs does not exhibit superconductivity down to 2 K.