Magneto-straintronics on a Co-coordinating metalloboronfullerene

The strain-modulated ultrafast spin dynamics of Co embedded exohedral boron fullerene $[\mathrm{Co}&{\mathrm{B}}₄₀{]}^{\ensuremath{-}}$ is investigated with high-level ab initio calculations. We find that due to its high ductility and malleability, ${\mathrm{B}}₄₀$ can retain its structure upon both the addition of a magnetic atom and the exertion of mechanical tensile or compressive strain, and that its elasticity modulus is highly anisotropic. The geometric optimization reveals that $[\mathrm{Co}&{\mathrm{B}}₄₀{]}^{\ensuremath{-}}$ prefers three different configurations. For the spin-dynamics investigation we focus on one of them, namely the configuration with the Co located near the center of a heptagon (the only geometry in which the boron cage remains intact) as an example to investigate the spin-dynamics features. Several laser-induced spin-flip scenarios are suggested, the details of which strongly depend on the magnitude and the direction of any deformations. Thus, utilizing the coupling between the external mechanical strain and the spin degree of freedom in magnetic exohedral all-boron fullerenes, we demonstrate the realizability of magnetostraintronic devices on molecular systems. The asymmetric modulation of the spin-flip process with respect to the tensile and compressive strain (tension-compression-asymmetric ultrafast spin dynamics) can provide further control of such integrated spin-logic devices.