Short Summary
In intermetallic compounds, the realized materials properties are governed by the actual atomic arrangements. We will study the effect of disorder by correlating mainly neutron diffraction experiments with measurements of macroscopic parameters and derive pertinent microscopic models. This will be done specifically in Ni$_2$Mn-based Heusler systems, which display functional potentials including, eg{}, large ferromagnetic shape-memory and magnetocaloric effects as well as ferromagnetic half-metallicity.