Magnetism and the magnetocaloric effect in PrMn1. 6Fe0. 4Ge2

The magnetic and magnetocaloric properties of PrMn1.6Fe0.4Ge2around the ferromagnetic transitions T C inter ~ 230 K and T C Pr ~ 30 K have been investigated by magnetisation, 57Fe Mössbauer spectroscopy and electron paramagnetic resonance (EPR) measurements over the temperature range 5–300 K. The broad peaks in magnetic entropy around TC inter (intralayer antiferromagnetism of the Mn sublattice to canted ferromagnetism) and TC Pr (onset of ferromagnetic order of Pr sublattice in addition to ferromagnetically ordered Mn sublattice) are typical of second order transitions with maximum entropy values of -ΔS M ~ 2.0 J/kg K and -ΔS M ~ 2.2 J/kg K respectively for ΔB = 0–6 T. The EPR signal around T = 48 K of g value g ~ 0.8 is consistent with paramagnetic free ion Pr3 + . Below TC Pr ~ 30 K the g value increases steadily to g ~ 2.5 at 8 K as saturation of the Pr3 +  ion is approached. The EPR measurements indicate additional effects in this system below T ~ 20 K with the appearance of EPR signals of low g value g ~ 0.6.