MAGNETIC-PROPERTIES, SPECIFIC-HEAT STUDIES AND MOSSBAUER MEASUREMENTS OF PRBA2NBCU2O8

PrBa2NbCu2O8 has been studied by DC susceptibility and specific heat measurements to determine the magnetic behavior of the Pr sublattice, and by a 1% Fe-57-doped sample to determine the magnetic behavior of the Cu (2) sites. The Pr sublattice and the CuO2 planes are both antiferromagnetically ordered at 11.6 and 360 K, respectively. The Pr contribution to the specific heat DELTAC(p)(T) was calculated by subtracting the data of LaBa2NbCu2O8 as background. The entropy associated with the magnetic transition is 6.7 J/mol K, intermediate between the expected values for Pr4+ and Pr3+. At low temperatures the magnetic contribution has the form of DELTAC(p)(T) = MT3.1 characteristic of 3D antiferromagnetic magnons. In contrast to PrBa2Cu3Oz, no linear term for the electronic specific heat is observed in PrBa2NbCu2O8.