A chemically inert Rashba split interface electronic structure of C60, FeOEP and PTCDA on BiAg2/Ag(111) substrates

Maren C Cottin,Johannes Schaffert,Andrew L Walter,Jorge Lobo-Checa,Christian A Bobisch,J Enrique Ortega,Rolf Möller

doi:10.1088/1367-2630/16/4/045002

Maren C Cottin, Johannes Schaffert + Show 5 more

Open Access

https://doi.org/10.1088/1367-2630/16/4/045002

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Abstract

The fields of organic electronics and spintronics have the potential to revolutionize the electronics industry. Finding the right materials that can retain their electrical and spin properties when combined is a technological and fundamental challenge. We carry out the study of three archetypal organic molecules in intimate contact with the BiAg2 surface alloy. We show that the BiAg2 alloy is an especially suited substrate due to its inertness as support for molecular films, exhibiting an almost complete absence of substrate–molecular interactions. This is inferred from the persistence of a completely unaltered giant spin-orbit split surface state of the BiAg2 substrate, and from the absence of significant metallic screening of charged molecular levels in the organic layer. Spin-orbit split states in BiAg2 turn out to be far more robust to organic overlayers than previously thought.

Highlights

The question arises as to what extent the Rashba splitting in surface alloys can be preserved upon adsorption of functional, organic molecules
The hole injection barrier (HIB) for this substrate remains almost constant from the monolayer to the thick film, which is of particular importance when envisaging electronic devices
Investigations of the electronic structure of C60, FeOEP and PTCDA films on BiAg2/Ag(111) substrates reveal that the giant spin-split surface state of the BiAg2 alloy remains unexpectedly unaffected under the three molecular films

Summary

Conclusion

Investigations of the electronic structure of C60, FeOEP and PTCDA films on BiAg2/Ag(111) substrates reveal that the giant spin-split surface state of the BiAg2 alloy remains unexpectedly unaffected under the three molecular films. No hybridization of the substrate d-bands and molecular bands is observed, with negligible energy variations of the overlayer molecular orbitals. Such weak substrate–molecule interactions are attributed to the complete filling of electron shells in the BiAg2 terminated Ag(111) surface. The hole injection barrier for the substrate remains almost constant throughout the studied molecular coverage. On the other hand, maintaining the substrate’s spin character and the electronic nature (hole injection barrier) of the organic overlayer could create novel devices capable of manipulating each component independently, envisaging a path toward the merging of organic electronic and spintronic devices

Methods

Findings

Funding sources