Combinatorial Development of Fe–Co–Nb Thin Film Magnetic Nanocomposites

Abstract

A Fe-Co-Nb thin film materials library was deposited by combinatorial magnetron sputtering and investigated by high-throughput methods to identify new noncubic ferromagnetic phases, indicating that combinatorial experimentation is an efficient method to discover new ferromagnetic phases adequate for permanent magnet applications. Structural analysis indicated the formation of a new magnetic ternary compound (Fe,Co)3Nb with a hexagonal crystal structure (C36) embedded in an FeCo-based matrix. This nanocomposite exhibits characteristics of a two-phase ferromagnetic system, the so-called hard-soft nanocomposites, indicating that the new phase (Fe,Co)3Nb is ferromagnetic. Magnetic hysteresis loops at various angles revealed that the magnetization reversal process is governed by a domain wall pinning mechanism.

High Magnetic Coercivity in Nanostructured Mn3O4 Thin Films Obtained by Chemical Vapor Deposition

“…To the best of our knowledge, the measured coercivity values are the highest among those previously reported for Mn 3 O 4 films, , and similar (or slightly lower/higher) values have been obtained only in nanoparticles ,,,,, and nanowires/rods − ,,, where surface/interface and shape anisotropy, respectively, were indicated as the main factors responsible for the observed effects. In the present case, the high coercivity values could be traced back to the presence of microstructural defects (see the above-discussed XRD results) acting as pinning sites for domain wall motion. − This observation accounts for the highest coercivity being observed for the Mn 3 O 4 specimen synthesized under dry O 2 at 10.0 mbar, which presented the larger amount of microstructural defects, as indicated by structural analyses (see above).…”

Combinatorial study of Fe-Co-V hard magnetic thin films

“…The domain wall pinning effect supported by the Kondorsky model is evidence that the precipitate hardening effect is likely from the cited γ-fcc precipitate phase acting as pinning sites for domain wall motion [5, 34] The scientific community largely accepts the idea; however, little hard evidence supports the claim other than correlation of the coercive field with the formation of precipitates. Further studies should include confirmation of the proposed 180° pinning mechanism.…”

“…We have studied alloys of Fe and Co with refractory metals including W [3], Mo [4], Nb [5], and V (this work) as part of our search for rare-earth-free permanent magnets using the combinatorial methodology. These refractory metal additions are stable at a temperature of 200°C, as required for traction motors.…”

Discovery of new materials using combinatorial synthesis and high-throughput characterization of thin-film materials libraries combined with computational methods

“…New non-cubic ferromagnetic phases for permanent magnet applications can be searched for in Fe-Co-X thin-film MLs by high-throughput MOKE: in a Fe-Co-Nb composition spread, a new magnetic compound (Fe,Co) 3 Nb with C36 structure, embedded in a FeCo-based matrix was identified. 30 Increased chemical complexity Increased chemical complexity can lead to improved functional properties e.g. 31 Compositional effects on the light-induced oxygen evolution in co-deposited Bi(V-Mo-X)O 4 MLs (X = Ta, W, Nb) were unraveled using an optical scanning droplet cell.…”