Regresar

Neutron diffraction study of phase separation in the Pr0.5-δCa0. 2+δSr0.3MnO3 manganite around half doping

Abstract:

This article studies the intrinsic influence of hole doping (n=0.5+δ) on the structural and magnetic phases of the Pr0.5-δCa0.2+δSr0. 3MnO3 ceramic manganite. Neutron thermodiffractograms are reported for samples with n=0.46, 0.48, 0.50, 0.52, and 0.54 (δ=-0.04,-0.02,0.0,0.02,0.04) in the temperature range 10K≤T≤300K, as well as high-resolution neutron-diffraction experiments for selected samples and temperatures. We observe structural and magnetic phase coexistence for all the studied compositions and discuss the temperature evolution of the lattice parameters, phase fractions, and magnetic moments of the observed phases. For hole dopings n<12, the ground state at low temperature is ferromagnetic, while for n>12, it is CE-type antiferromagnetic with Mn3+ and Mn4+ spatial order. An extra A-type antiferromagnetic phase is also observed for n>12. Our results clearly show the strong coupling between the structural phases and the macroscopic magnetic behavior of the system. The temperature dependence of the magnetization and the hole doping influence are discussed in terms of phase separation. © 2005 The American Physical Society.