ANTIFERROMAGNETISM IN AU5MN2

The intermetallic compound Au5Mn2 has been investigated by neutron diffraction and x-ray techniques and the temperature variations of the magnetic susceptibility, electrical resistivity and Young's modulus have been measured. The compound is shown to be antiferromagnetic with a Néel temperature of 353°K, and to have identical chemical and magnetic unit cells. Each contains four manganese atoms with ionic moments of spin S = fraction five-twos arranged in a co-linear antiferromagnetic array. Above the Néel temperature the magnetic susceptibility showed Curie-Weiss behaviour, with a Curie temperature of +100°K. Characteristic antiferromagnetic anomalies were also observed in the temperature variation of resistivity and Young's modulus.