Inelastic neutron scattering and heat capacity studies of ferromagnetic PrInNi4

PrInNi4 is a particularly interesting magnetic system which may be compared with PrNi5, a Van-Vleck paramagnet displaying nuclear magnetic ordering below 0.4 mK. Our heat capacity measurements on PrInNi4 reveal that it undergoes a ferromagnetic transition at TC = 0.75 K and show that TC rises dramatically with field, such that TC = 9 K at 6 T. We have determined the magnetic excitations in PrInNi4 using the HET spectrometer at ISIS. The lowest energy mode softens as q → 0, consistent with the low temperature ferromagnetic order. © 2006 Elsevier B.V. All rights reserved.