Specific Heat on Metamorphic and Iron-Doped GdBa₂Cu₃O_7-δ

Abstract

Magnetic ordering and lattice properties were studied through low-temperature specific heat on metamorphic and Fe-doped GdBa 2 Cu 3 O 7-δ . The orthorhombic to tetragonal (O-T) phase transition due to an increase of the parameter δ in GdBa 2 Cu 3 O 7-δ causes a decrease of the Debye temperature θ D , together with the rapid drop of superconducting transition temperature T c , while causing no significant change in the Néel temperature T N . This is compared with the result for GdBa 2 (Cu 1- x Fe x ) 3 O 7-δ , where the values of T N and θ D as well as T c are insensitive to the variation of x during the course of O-T transition.