Mössbauer Study of Iron-Arsenic Compounds

Abstract

The magnetic properties of the iron-arsenic compounds Fe₂As, FeAs and FeAs₂ have been studied with the Mössbauer effect of ⁵⁷Fe. Fe₂As has a Néel temperature of 353K and its magnetic moments align perpendicularly to the c-axis. These results are in agreement with the neutron diffraction measurements. The temperature variations of both the quadrupole interaction and the isomer shift suggest the onset of a second-order magnetic transition at the Néel temperature. FaAs₂ shows a doublet associated with quadrupole interactions at 5 K, leading to no magnetic ordering even at low temperatures. The broad absorption spectrum of FeAs at 5 K indicates a magnetic ordering at low temperatures.