Engineering Magnetic Hybridization at Organic–Ferromagnetic Interfaces by C60-Adsorption-Induced Fe(001) Surface Reconstruction

Large magnetoresistance has been reported for C60-based vertical spin valves. But for the underlying organic–ferromagnetic interfacial atomistic structures, both experimental and theoretical works have assumed unreconstructed atomic structures for the magneticsurfaces, although organic molecule (e.g., fullerene and thiolate) adsorption frequently induces nonmagneticsurfaces reconstruction. Here we report that C60adsorption can induce a prototype ferromagnetic surface, Fe(001), reconstruction, via thorough structural search from first-principles calculations. We propose that Fe(001) surface reconstruction should already occur under the reported annealing temperature in literature. Reconstruction solidifies C60/Fe interface bonding and enhances C60spin-polarization. More importantly, only our reconstructed structure can explain the experimental observation of an inversion of C60spin-polarization around Fermi-level relative to that of Fe substrate, which is attributed to the C60lowest unoccupied molecular orbitals LUMO-derived states are shifted to Fermi level by charge transfer and to the strong coupling in the reconstructed structure. One could expect that surface reconstruction occur not only at the C60/Fe(001) interface, but also at interfaces of other molecule-magnetic metals. Hence our work offers a new pathway to interface engineering, that is, via surface reconstruction to manipulate spintronic properties and promote the field of interface-assisted spintronics.