Anisotropy and orbital moment in Sm-Co permanent magnets

Authors

Bhaskar Das, University of Nebraska-Lincoln
Renu Choudhary, Iowa State University
Ralph Skomski, University of Nebraska-Lincoln
Balamurugan Balasubramanian, University of Nebraska-Lincoln
Arjun K. Pathak, Iowa State University
Durga Paudyal, Iowa State University
David J. Sellmyer, University of Nebraska - LincolnFollow

Date of this Version

7-18-2019

Citation

BHASKAR DAS et al. PHYSICAL REVIEW B 100, 024419 (2019). DOI: 10.1103/PhysRevB.100.024419

Comments

Used by permission.

Abstract

Structural and magnetic properties of iron-free and iron-substituted SmCo₅ have been investigated theoretically and experimentally. The nanocrystalline ribbons of SmCo_5−xFe_x (0 [] x [] 2), which were produced by rapid solidification, crystallize in the hexagonal CaCu₅ structure for x [] 0.75. Small Fe additions (x = 0.25) substantially improve the coercivity, from 0.45 to 2.70 T, which we interpret as combined intrinsic and extrinsic effect. Most of our findings are consistent with past samarium-cobalt research, but some are at odds with findings that have seemingly been well established through decades of rare-earth transition-metal research. In particular, our local spin-density approximation with Hubbard parameter calculations indicate that the electronic structure of the Sm atoms violates Hund’s rules and that the orbital moment is strongly quenched. Possible reasons for the apparent disagreement between theory and experiment are discussed. We explicitly determine the dependence of the Sm 4ƒ charge distribution, arguing that an accurate density-functional description of SmCo₅ is a challenge to future research.