Naslov
Cesium on graphene on Ir(111): adsorption, intercalation and desorption

Autori
Petrović, Marin ; Šrut, Iva ; Pletikosić, Ivo ; Pervan, Petar ; Milun, Milorad ; Runte, Sven ; Busse, Carsten ; Michely, Thomas ; Sadowski, Jurek ; Valla, Tonica ; Kralj, Marko

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Skup
European Workshop on Epitaxial Graphene

Mjesto i datum
Aussois, Francuska, 27.01.2013. - 31.01.2013

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
graphene, iridium, intercalation, wrinkles, ARPES, LEEM, STM

Sažetak
Adsorption and intercalation of various substances to epitaxial graphene gives rise to hybrid systems with novel topographical and electronic properties [1]. One of the most commonly used intercalation substances are alkali atoms know for their high levels of chemical doping of graphene [2, 3]. However, the mechanism of alkali intercalation i.e. a microscopic view of an atom transport across the graphene sheet is still unclear. Here we present a study of a cesium + graphene/Ir(111) system at various stages involving cesium adsorption, intercalation, and desorption. By utilizing scanning tunneling microscopy (STM) we were able to characterize emerging structures at the atomic scale. Complementary, low-energy electron microscopy (LEEM) revealed cesium intercalation and desorption dynamics in real time on micron scales and clearly showed a strong influence of graphene wrinkles and iridium steps on the intercalation process. Angle-resolved photoemission (ARPES) was used to characterize chemical doping of graphene on individual phases. In detail, we have shown that cesium atoms do not intercalate immediately once they are deposited on the graphene surface. First they form a diluted “on top” phase up to a maximum (7×7) concentration. Denser phases of adsorbed Cs are energetically less favorable and it pays off to intercalate cesium atoms below graphene at a cost of its delamination from the substrate. We found that it is possible to achieve coexistence of well defined “on top” and intercalated Cs-phases. Transport of cesium under graphene takes place at cracks on graphene wrinkles. The desorption process revealed once more the importance of graphene topography and in particular the delamination/relamination processes to the dynamics of such hybrid systems. Our results contribute to the understanding of intercalation under graphene in detail and can be used to form more general picture for graphene intercalation with other chemical species. [1] R. Balog et al., Nature Mater. 9, 315 (2010) [2] J.L. McChesney et al., Phys. Rev. Lett. 104, 136803 (2010) [3] I. Pletikosić et al., Phys. Rev. B 155447 (2012)

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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