A variable temperature neutron diffraction study of the layered perovskite YBaMn2O5

Abstract

A variable temperature neutron diffraction study has been carried out on the layered perovskite YBaMn₂O₅ between 100 and 300 K. A broad peak indexed as (1/2, 1/2, 1) on the nuclear cell is consistent with short range Mn^II /Mn^III valence ordering. The magnetic structure below the ferrimagnetic ordering temperature of 167 K has been determined and is in agreement with a previously proposed model. Changes in lattice parameters, bond lengths and angles show evidence of an exchange striction at T_C .