Ultra-low damping in 3D metal alloys

The reduction of the magnetic damping parameter has a crucial role for key applications in spintronics. It is very important in Magnetic Tunnel Junction, for instance. Low damping values had been predicted for metallic Co_xFe_1-x alloys about x = 0.20, which was unexpected for metallic magnetic materials [1]. A group from NIST in collaboration with groups of Regensburg and Uppsala Universities have shown recently experimentally ultra-low magnetic damping constant in those alloys [2]. The study takes advantage of ferromagnetic resonance for the experimental determination of damping constant and supports their results with first principles calculations. This new results makes Co_0.20Fe_0.80 - Co_0.25Fe_0.75 alloys very attractive for new experiments and applications in spintronics. Indeed, it has been shown previously that these alloys also exhibit zero magneto-crystalline anisotropy and high tunnel magnetoresistance for this composition range.

[1] S. Mankovsky, D. Ködderitzsch, G. Woltersdorf, and H. Ebert, First-principles calculation of the Gilbert damping parameter via the linear response formalism with application to magnetic transition metals and alloys, Phys. Rev. B 87, 014430 (2013)

[2] Martin A. W. Schoen, Danny Thonig, Michael L. Schneider, T. J. Silva, Hans T. Nembach, Olle Eriksson, Olof Karis & Justin M. Shaw, Ultra-low magnetic damping of a metallic ferromagnet, Nature Physics 12, 839–842 (2016)

Suggested by: S. Berger (OMNT), Juan Carlos Rojas Sanchez (Nancy, France).