Magnetic structure and magneto-volume anomalies in Er2Fe17 compound

Neutron powder diffraction shows that the intermetallic Er₂Fe₁₇ compound with hexagonal crystal structure has a ferrimagnetic ground state (T_C = 303 K). At T = 5 K the magnetic moments of Fe sublattice (μ ~ 2 μ_B) are therefore antiparalell to those of the Er one (μ ~ 9 μ_B), all of them lying on the basal plane. This compound exhibits strong magneto-volume effects up to temperatures in the vicinity of T_C. Neutron thermo-diffraction experiments also show an anomalous temperature dependence of the cell volume, including a negative thermal expansion coefficient below 300 K. In addition, a positive spontaneous volume magnetostriction is observed up to T ~ 400 K, with a maximum (ω_S ~ 0.02) located at T = 5 K.