Magnetic studies of Ta doping in Pr1.5Ce0.5Sr2Cu2NbO10

The Pr1.5Ce0.5Sr2Cu2Nb1-xTaxO10 (0≤x≤1) compounds display an in-plane weak ferromagnetic component similar to that observed in the Nd2CuO4-type T' structure. Zero-field-cooled and field-cooled magnetization spectra indicate that the magnetic peak, previously ascribed by neutron diffraction in the Pr1.5Ce0.5Sr2Cu2NbO10 system as originating from an interlayer Cu spin reorientation, shifts towards lower temperature as the content of Ta increases. In addition, the effective Pr ion moment obtained by Curie-Weiss fits to the magnetization data taken at fields sufficiently high to saturate the weak ferromagnetic component indicate that the long-range antiferromagnetic ordering of the Pr ions in these compounds (∼2.8μB) is not affected by the substitution of Ta in for Nb. The nature of the complex magnetic behavior of these compounds originates from a thermal competition between magnetocrystalline anisotropy and magnetic exchange interactions. copyright 1996 The American Physical Society