Neutron powder diffraction study of the nuclear and magnetic structures of [formula omitted] ( [formula omitted], and 0.15)

Abstract

A comparative study of the nuclear and magnetic structures of LaMn 1 - x Cr x O 3.00 perovskite ( x = 0.05 , and 0.15) is reported. Cr 3 + is isoelectronic with Mn 4 + ( 3 d 3 ) and is also a non-Jahn–Teller ion. Both magnetic ions increase the hole (empty e g levels) concentration and decrease the Jahn–Teller distortion. To characterize the interaction established between Mn 3 + and Cr 3 + and the effect of Cr 3 + on the magnetic structure, samples without Mn 4 + were synthesized. X-ray powder diffraction, at room temperature, reveals the existence of single phase materials with orthorhombic symmetry (Pnma) for all the studied samples. Magnetic data shows an increase of the FM interaction with Cr content. Magnetic phases change from A-type antiferromagnetic order to a system with magnetic clusters through a spin-glass-like phase. In order to fully understand the magnetic phase diagram, neutron powder diffraction was carried out. Both, nuclear and magnetic structures are studied as a function of temperature and Cr content. These results reveal the presence of more than one magnetic phase and a clear change of the spin orientation with temperature and Cr content. The mixture of magnetization and neutron powder diffraction data allow us to describe the role of the Cr 3 + on the magnetic properties.