About this Abstract |
Meeting |
2020 TMS Annual Meeting & Exhibition
|
Symposium
|
Advanced Magnetic Materials for Energy and Power Conversion Applications
|
Presentation Title |
Anisotropy and Orbital Moment in Rare Earth - Cobalt Permanent Magnets |
Author(s) |
Durga Paudyal, Renu Choudhary, Ralph Skomski |
On-Site Speaker (Planned) |
Durga Paudyal |
Abstract Scope |
Many features of Fe substituted R-Co systems are consistent with past research, but some are seemingly contradictory. The disagreement reflects how the many-electron nature of the rare-earth 4f electrons is interpreted by crystal-field and local spin density approximation with Hubbard model and spin-orbit-coupling (LSDA+U+SOC) theories. The two-sublattice crystal-field theory describes a broad variety of Sm-Co properties, such as the temperature dependence of magnetization and anisotropy, but it is not a first-principle approach. By contrast, our first-principle approach, LSDA+U, yields a substantial orbital-moment quenching, which violates Hund's rules and is contradictory to conventional knowledge accumulated over several decades of rare-earth research. Rationalizing the orbital-moment quenching in terms of the dependence of the 4f-charge distribution on the magnetization angle, we argue that medium- and long-run future research will be necessary to reconcile experiment, sublattice models, and first-principle calculations. This work is supported by the CMI. |
Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |