Electronic excitations in correlated finite 2D materials generated by ion impact

The impact of ions on solid targets is of high interest in many fields and has been extensively treated in linear response. However, ions give rise to a very strong, highly localized and fast excitation that my well lead to nonlinear and nonadiabatic effects. The ion-initiated dynamics are particularly interesting in strongly correlated materials giving rise to nontrivial electronic processes such as the excitation of doublons [1]. We present a time-resolved analysis of these processes in finite 2D graphene-type clusters, using a

nonequilibrium Green functions (NEGF) approach. While NEGF can handle any dimensionality and geometry, however, they are computationally costly (cubic scaling with the simulation duration T).  Recently, we could achieve linear scaling with T by introducing the G1-G2 scheme [2]. It has allowed us to perform long simulations and, in addition, to include higher order electronic selfenergies accounting for strong coupling and dynamical screening. We use this to explore the doublon generation by multiple ion impacts [3] and the charge transfer between target and projectile [4].  

[1] K. Balzer et al., Phys. Rev. Lett. 121, 267602 (2018)

[2] N. Schluenzen et al., Phys. Rev. Lett. 124, 076601 (2020)

[3] L. Borkowski et al., phys. stat. sol. (b)  (2021), arXiv:2110.06644

[4] K. Balzer and M. Bonitz, Contrib. Plasma Phys. e202100041 (2021)