Semiconducting and magnetic properties of FeS-derived compounds (C2H8N2)xFeS and Ax(C2H8N2)yFeS (A = Li, Na).

Several FeS-derived intercalated compounds (C2H8N2)xFeS and Ax(C2H8N2)yFeS (A = Li, Na) were successfully synthesized via a novel ammonothermal method. The powder X-ray diffraction (XRD) measurements reveal that the FeS intercalated samples have the same tetragonal crystal structure as the parent FeS. After intercalation, these three as-synthesized samples do not show superconductor behavior, which is confirmed by the magnetization and the electrical resistivity measurements. (C2H8N2)xFeS exhibits paramagnetic semiconductor behavior, while the newly synthesized Ax(C2H8N2)yFeS (A = Li, Na) shows antiferromagnetic semiconductor behavior. The absence of superconductivity in these FeS-derived compounds should be closely related to the iron vacancies in the FeS layer.