2009/12/01 by F. Liot, C. Hooley, Liot, F. +2
Engineering · Materials Science · Physics and Astronomy · #FOS: Physical sciences #Magnetic Properties and Applications #Magnetic properties of thin films #Materials Science (cond-mat.mtrl-sci) #Microstructure and Mechanical Properties of Steels #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.0912.0215
4 pages, 5 figures, PRL format; slight updates to figures and revisions to the text (including title and abstract)
openalex publication_date 2009/12/01 · arxiv created 2010/10/08 · arxiv updated 2010/10/11 · openalex created_date 2019/07/30 · openalex updated_date 2026/07/28
Using first-principles calculations, in conjunction with Ising magnetism, we undertake a theoretical study to elucidate the origin of the experimentally observed Invar effects in disordered fcc iron-based ferromagnets. First, we show that our theory can account for the Invar effects in iron-nickel alloys, the anomalies being driven by the magnetic contributions to the average free energies. Second, we present evidence indicating that the relationship between thermal expansion and magnetism is essentially the same in all the studied alloys, including those which display the Invar effect and those which do not. Hence we propose that magnetism plays a crucial role in determining whether a system exhibits normal thermal expansion, the Invar effect, or something else. The crucial determining factor is the rate at which the relative orientation of the local magnetic moments of nearest-neighbor iron atoms fluctuates as the system is heated.