| AVS 63rd International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS1+AS+HC+NS-TuM |
| Session: | Surface Dynamics, Non-Adiabaticity, and Theory and Modeling of Surface and Interfacial Phenomena |
| Presenter: | Talat Rahman, University of Central Florida |
| Authors: | S. Hong, University of Central Florida T.S. Rahman, University of Central Florida |
| Correspondent: | Click to Email |
We have performed density functional theory based calculations to compare the characteristics of the interface of Fe-Ag and Fe-Cr multilayers. A perfect interface lattice match between the Fe and Ag layers was obtained by rotating fcc Ag(100) layers by 45° on bcc Fe(100). On the other hand, the Fe-Cr interface could be modeled by epitaxial layers of bcc Fe(100) and Cr(100). In Fe-Ag multilayers, we find the signature peak of Fe bulk phonons (35 meV) to be completely diminished, while the low energy peaks are remarkably enhanced, in agreement with experiment [1]. In contrast, the phonon density of state in the Fe-Cr multilayers do not show any salient feature except a slight decrease in the 35 meV peak for the Fe layer at the interface, as compared to that of the middle Fe layer, again in agreement with experiment [2]. The magnetic moment of the interfacial Fe atoms is larger than that of Fe atoms in other layers, as a result of charge transfer from Fe to Ag at the interface. As compared to the middle layers, more spin-up and less spin-down states are occupied at the interface in such a way that Fe donates a large number of spin-down electrons to Ag but receives only a few spin-up electrons from the latter because of the almost fully occupied Ag d-band. This leads to rather unstable Fe-Ag interface. On the contrary, at the Fe-Cr interface, Cr can easily give and take electrons leading to smooth interfacial coupling and stable environment.
[1] B. Roldan Cuenya et al., to be published
[2] Roldan et al, Phys. Rev. B 77, 165410 (2008).
Work supported in part by DOE Grant No. DOE-DE-FG02-07ER46354