Specific heat of pure Y<inf>1-x</inf>Pr<inf>x</inf>Ba<inf>2</inf>Cu<inf>3</inf>O<inf>7-δ</inf> single crystals in magnetic fields

Specific heat measurements have been performed on single crystals of Y1-xPrxBa2Cu3O1-δ (x=0.33, 1) in the temperature range 2 K<T<50 K with magnetic fields up to 7.5 T, both parallel and perpendicular to the c-axis. The crystals were grown in BaZrO3 crucibles and therefore the possibility of crucible contamination in the crystals is reduced to a large extent. A large linear term with γ=207 mJ/mol K2 was determined for x=1 and the crystal field contribution due to Pr ion was calculated for both the samples. The transitions were found to be sharp lambda type for x=1 with the ordering temperature at 16.6 K and very broad for x=0.33 with the transition temperature below 2 K. Also, the transition temperatures increased for x=0.33 and decreased for x=1 with increasing magnetic fields indicating a different type of interaction for these two samples. The coupling in the ab plane was found to be stronger than in the c-axis. © 1997 American Institute of Physics.