Absence of hysteresis in the heat capacity of the three-dimensional   random-field Ising model
  Heat capacity measurements on the prototypical three-dimensional random-field Ising model compound Fe0.58Zn0.42F2 have been performed in both of the field-cooling (FC) and zero-field-cooling (ZFC) procedures. There is no evidence of hysteresis between the FC and ZFC protocols within the experimental accuracy. The absence of hysteresis is interpreted based on a magnetic field (H)-temperature (T) phase diagram in which a metastability region exists between the Neel temperature line Tn(H) and Hc1(T), the latter being the lowest critical field line for the local spin flips. 
J. Satooka (Ochanomizu Univ.), H. Aruga Katori, A. Tobo and K.   Katsumata (RIKEN)