Despite the venerability of the subject, the mechanisms responsible for the Invar effect, though thought to be related to Invar's complex magnetic behavior, are still deeply mysterious. The calculations were initialized by setting the orientations of the magnetic moments on individual Fe and Ni atoms to point in random directions. The magnetic moments were then allowed to relax into their equilibrium configuration. The results, shown on the left, point to unusual magnetic behavior involving non-collinear arrangements of the local magnetic moments associated with Fe rich clusters within the otherwise disordered alloy. These magnetic structures have important implications for our understanding of magnetism in this material, implications that are currently being investigated experimentally using neutron diffraction.
Magnetic materials represent a multi-billion dollar industry.
Yet, despite this great driving force, a microscopic understanding of metallic magnetism has proved to elusive. The methods that are being developed, coupled with the availability of massively parallel computers, will provide the necessary tools to perform realistic simulations on many of these problems and have the potential to enable significant advances in magnetic materials research and development. Ni 35 Invar alloys. Note moments that point in directions opposite and non-colinear to the prevailing direction. View of non-colinear Fe and Ni moments projected onto a common Fe and Ni origin.