Neutron diffraction study and magnetic properties of LaMn1-xGaxO3 -: art. no. 174431

The LaMn1-xGaxO3 series (x=0.05, 0.1, 0.15, 0.3, 0.4, 0.5, 0.6, 0.8, 0.9) was studied by means of ac magnetic susceptibility, magnetization, and neutron diffraction as a function of temperature. The crystal and magnetic structures have been refined from the neutron diffraction data. The replacement of Mn by Ga induces a continuous decrease of the tetragonal distortion of the MO6 (M=Mn,Ga) octahedron, being practically regular for xgreater than or equal to0.6. Simultaneously, the Ga substitution induces a ferromagnetic component explained in terms of a canting of the A-type antiferromagnetic structure. The ferromagnetic component increases with increasing the Ga content up to x=0.5, where a collinear ferromagnetism is observed. For xgreater than or equal to0.6, the system evolves from collinear ferromagnetism into superparamagnetism. The occurrence of superparamagnetism for heavily doped samples (x=0.8 or 0.9) suggests that Mn atoms tend to form clusters.