Magnetovolume anomalies in Ce[sub 2]Fe[sub 17-x]Mn[sub x].

The small nonmonotonic changes of the lattice parameters upon the substitution of Mn for Fe in Ce[sub 2]Fe[sub 17] lead to significant changes of the magnetic properties. In order to determine the role of the volume, we made ac susceptibility and thermal expansion measurements on the polycrystalline compounds Ce[sub 2]Fe[sub 16.65]Mn[sub 0.35] and Ce[sub 2]Fe[sub 16]Mn[sub 1] under hydrostatic pressure up to 10 kbar in the temperature range 10-300 K. The substitution of Mn for Fe leads to significant narrowing of the range of stability of the low-temperature ferromagnetic phase characterized by Θ[sub T]=48 K (x=0.35) in comparison with binary Ce[sub 2]Fe[sub 17], where Θ[sub T]=94 K. Applying a relatively small pressure of 1.5 kbar leads to suppression of both the ferromagnetic order and large positive spontaneous volume magnetostriction in Ce[sub 2]Fe[sub 16.5]Mn[sub 0.35]. The pressure effect on Θ[sub T] is significant, dΘ[sub T]/dp=-30 K/kbar. The effect of pressure on the Néel temperature is moderate and increases slightly, with increasing Mn content (dT[sub N]/dp=-2.2 K/kbar for Ce[sub 2]Fe[sub 16.65]Mn[sub 0.35]). No ferromagnetic order was observed in Ce[sub 2]Fe[sub 16]Mn[sub 1] at ambient pressure, but an unexpected reentrant increase of the ac susceptibility was detected at pressures higher than 1.5 kbar below 50 K. It indicates the existence of a pressure-induced ferromagnetic phase at low temperature. The results show not only a strong correlation between the magnetic properties and the lattice volume but also a significant role of the Mn content. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]