Routes for enhanced magnetism in Ni-Mn-In metamagnetic shape memory alloys

Abstract We provide in-depth physical insight into the enhancement of the magnetic properties of metamagnetic shape memory alloys produced by thermal treatment and cobalt doping. We use neutron scattering to study the atomic order and magnetic structures in the austenitic phases of Ni 50 Mn 34 In 16 and Ni 45 Co 5 Mn 37 In 13 alloys in two different states induced by thermal treatments. The increase of the magnetization in the austenite phase, particularly by cobalt doping, is explained by the enhanced ferromagnetic coupling between the magnetic moments located in octahedral sites. The spin density maps obtained from polarized neutron diffraction reveal the magnetic interaction pathways responsible for this coupling scheme.