Atomic structure and magnetism of ordered and disordered Al0.5Fe0.5-xMnx alloys

The equiatomic FeAl alloy has been modified by partial substitution of Mn f or Fe, and its magnetic and structural properties investigated by neutron d iffraction (ND), x-ray absorption fine structure (XAFS) spectroscopy, Mossb auer spectroscopy (MS), and SQUID magnetometry both for the ordered (B2) an d disordered states. The unit cell volume is measured to increase linearly with Mn concentration. XAFS measurements indicate local structural displace ments occur at the Mn sites in both ordered and disordered states that may act to frustrate long-range magnetic order (LRMO). Although MS and ND show no evidence of LRMO, SQUID magnetometry indicates an induced movement in th e ordered state that increases with disorder but does not saturate at field s up to 5 T. (C) 1999 American Institute of Physics. [S0021-8979(99)15408-2 ].