Low-field negative magnetization and coercive-field magnetization reversal in transition metal chalcogenides; Cr2FeSe4 magnetic structure from neutron diffraction

Low-field negative magnetization, of the order of −10−1 emu/g-Oe, from 4.2 K up to room temperature and higher (350 K), and coercive-field magnetization reversal are both present in Cr(3−x)FexX4 for X=S, Se, Te and x=0 to 3, and for Cr5Te8 and Cr7Te8. For Cr2FeSe4 the zero-field-cooled (ZFC) magnetization is negative for 5 Oe and below. To obtain a more detailed knowledge of the magnetic phases involved in the observed magnetization versus temperature M(T) curves, we obtained and studied neutron diffraction (n.d.) scans on the compound Cr2FeSe4, taken at 14 temperatures from 4.2 to 300 K. For this same n.d. sample, the temperature for magnetization reversal of value −3×10−4 emu/g-Oe is 80 K in 40 Oe applied field, then the reversal disappears for 65 Oe applied field. The complex magnetic interactions responsible for this reversal are revealed in the hysteresis curves.