Specific-heat anomaly of metamagnetism on PrFe4P12 and UCoAl

The field dependence of specific hear has been measured at low temperatures in order to study two different types of f-electron metamagnetic systems. The antiferromagnet PrFe4P12 with Neel temperature of 6.4 K shows a sharp p eak structure in CIT at the spin flip metamagnetic transition. In the high field state, the magnetic contribution C-m/T shows an anomalous huge value similar to 1.4 J/K-2 mol. UCoAl shows the metamagnetic transition from para magnetic ground state at similar to 1 T. where C/T at 0.5 K shows an appare nt decrease reflecting a change of the density of states. In the low-field state. ferromagnetic spin-fluctuation dominates in an anomalous temperature dependence of C. (C) 2000 Elsevier Science B.V. All rights reserved.