Spin-dependent electron transfer dynamics: key role of bandstructure*

We investigate theoretically the charge transfer dynamics of core-excited Ar on Co(001) and Fe(110). For these systems, recent core-hole-clock measurements [1] of the lifetime of the photo-excited 4s level of Ar* have shown a clear dependence on the spin of the excited electron. Minority electrons decay significantly faster than majority electrons. We investigate such processes using Green's functions techniques on top of density functional theory calculations, explicitly including the effect of the coupling to the semi-infinite substrate [2, 3]. Our results agree with the observed behavior and allow analyzing in detail the origin of this phenomenon. The key ingredient is the spin-depence of the bandstructure of the substrate and, in particular, the different positions of the Ar* 4s level within the projected band gap appearing around Gamma in the dispersive bands of Co(001) and Fe(110) for both spin channels. A simple model incorporating this effect successfully describes most of the observed phenomenology.
[1] F. Blobner, et al., Phys. Rev. Lett. 112, 086801 (2014)
[2] D. Sánchez-Portal, Prog. Surf. Sci. 82, 313–335 (2007)
[3] M. Müller, et al., J. Phys. Chem. C 122, 7575-7585 (2018)