Alloying route to tailor giant magnetic anisotropy in transition-metal nanowires

Abstract

First-principles theoretical investigations of one-dimensional ordered $3d$-$5d$ alloys reveal magnetic anisotropy energies $\ensuremath{\Delta}E$, which are extraordinary high for transition-metal nanostructures. The results show that $\ensuremath{\Delta}E$ of Pt-$X$ and Ir-$X$ wires with $X\ensuremath{\equiv}\text{Ti}$--Ni strongly oscillates as a function $3d$-band filling showing both giant values (e.g., $\ensuremath{\Delta}E=25$, 58, and 57 meV/atom for Pt-Ni, Ir-Cr, and Ir-Ni) as well as modest enhancements (e.g., $\ensuremath{\Delta}E=2.3$ and $6.5$ meV/atom for Pt-Cr and Pt-Fe). The robustness of the results with respect to strain and relaxation is demonstrated. The microscopic mechanisms behind the trends in $\ensuremath{\Delta}E$ are analyzed from a local perspective.