Abstract
Single-atom magnets, the ultimate limit of high-density magnetic storage, have attracted widespread attention over recent decades. However, they are far from being applicable as a storage medium because of their low magnetic stability. In this paper, we describe a strategy to induce huge magnetic anisotropy in ``bimetal magnets'' on a benzene (Bz) substrate based on the electron filling of $d$ orbitals. Our first-principles calculations reveal that OsX-Bz ($X=\mathrm{Fe}$, Ru, and Os) exhibits high structural stability, large unquenched orbital moments ($1.55--1.59\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{B}$), and huge perpendicular magnetic anisotropy energy (MAE) above 54.8 meV. The synergistic effect of two transition metal components toward this huge MAE and preserved orbital moment is discussed in depth, which is mainly attributed to the d-d coupling induced energy level rearrangement. Our work may provide insights into the underlying physical mechanism and bimetal molecule magnet design.
Highlights
The continuous downscale of magnetic storage devices would reach the ultimate limit scale–one atom stores one bit of information
IrCo-Bz has been studied by Xiao et al and its magnetic anisotropy energy (MAE) was about 248 meV calculated by an all-electron fullpotential local-orbital scheme [32]
We have investigated the stability and magnetic properties of transition metal dimers adsorbed on benzene using systematical first-principles calculations
Summary
The continuous downscale of magnetic storage devices would reach the ultimate limit scale–one atom stores one bit of information. A major breakthrough on magnetic materials is the discovery of single-molecule magnets with large MAE, as a result of reduced dimensionality and symmetry. Many multimetallic and bimetallic single-molecule magnets, such as small metal clusters and dimers, were found to exhibit good performance in terms of maintaining a stable magnetic orientation, enabling a MAE value of up to several hundred meV [1,2,3,4]. The magnetic centers of single-molecule magnets are generally 3d and 5d transition metal (TM) atoms. Their advantages are the large spin moment in 3d metal atoms and the strong SOC in the heavy 5d atoms, respectively.
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