Conversion of FeCo from soft to hard magnetic material by lattice engineering and nanopatterning

The development of magnetic materials with large uniaxial magnetic anisotropy (K-u) and high saturation magnetization has attracted much attention in various areas such as high-density magnetic storage, spintronic devices, and permanent magnets. Although FeCo alloys with the body-centred cubic structure exhibit the highest M-s among all transition metal alloys, their low K-u and coercivity (H-c) make them unsuitable for these applications. However, recent first-principles calculations have predicted large K-u for the FeCo films with the body-centred tetragonal structure. In this work, we experimentally investigated the hard magnetic properties and magnetic domain structures of nanopatterned FeCo alloy thin films. As a result, a relatively large value of the perpendicular uniaxial magnetic anisotropy K-u = 2.1 x 10(6) J.m(-3) was obtained, while the H-c of the nanopatterned FeCo layers increased with decreasing dot pattern size. The maximum H-c measured in this study was 4.8 x 10(5) A.m(-1), and the corresponding value of mu H-0(c) was 0.60 T, where mu(0) represented the vacuum permeability

Study of Magnetization Reversal Process in FeCo/Ru/FeCo Exchange Coupled Synthetic Antiferromagnetic Multilayers

FeCo/Ru/FeCo exchange coupled synthetic antiferromagnetic multilayers were prepared with two sputtering modes. One is continuous sputtering mode, and the other mode is layer-by-layer sputtering mode. The former mode implies that substrate faced the target and film growth process was continuous when FeCo layers were sputtering, whereas the latter implies that substrate was rotating with the mask at a speed of 5 rpm when FeCo layers were sputtering. It was found that the exchange coupling field Hex of sample sputtered by layer-by-layer mode was higher than the one sputtered by continuous mode. Domain structures were measured with applying varied in-plane magnetic fields along the easy axis in order to study the magnetization reversal process. We found it is a domain wall move process. When the applied field is smaller than Hex, both the two magnetic layers have domain structure and the domain structure of the two layers is reversed correspondingly. When the applied field is varying in the range of -Hex to Hex, the domain wall of the two layers moves correspondingly at the same time

Improvement of hard magnetic properties in microfabricated L10-FePt dot arrays upon post-annealing

application/pdf学術論文 (Article)科研費報告書収録論文(課題番号:16206067/研究代表者:高梨弘毅/自己形成面内変調人工格子の作製と磁気機能性材料への応用)230924 bytesjournal articl