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Modifying the electronic properties and magnetic interactions of the two-dimensional material silicene

Gill, TG; (2016) Modifying the electronic properties and magnetic interactions of the two-dimensional material silicene. Doctoral thesis , UCL (University College London). Green open access

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Abstract

As the pursuit for more powerful electronic devices progresses, individual components have had to be produced at ever smaller dimensions. Today, conventional technologies are at the edge of feasibility as they approach a fundamental limit at the atomic scale. Much research is aimed at overcoming the barrier to atomic scale devices, and indeed some of the explosion of interest into two-dimensional materials over the past decade has its roots in this goal. Graphene, the first atomically thin two-dimensional material, has since been followed by a growing number of intriguing materials with a wide variety of interesting properties, many of which may prove useful in technological devices. One of these two-dimensional materials is silicene, the silicon analogue to graphene that shares many of its properties. Moreover, owing to it being made of silicon, it may be more easily integrated into existing industrial processes. In this thesis, silicene grown upon conductive zirconium diboride is investigated by scanning tunnelling microscopy and spectroscopy. It is found that the structural and electronic properties of epitaxial silicene can be fine-tuned by depositing small amounts of silicon on its surface. However, with continued silicon deposition a significant change is observed: the additional silicon leads to the formation of a layered metallic silicon nanostructure that could be utilised as an atomically precise metallic contact to silicene. Beyond this, the magnetic interactions of individual cobalt atoms on the silicene surface are investigated and it is found that the combination of the semiconducting silicene surface with the metallic zirconium surface yields an unusual spatially distributed Kondo effect. When cobalt atoms are in close proximity to one another on the silicene surface, they exhibit an incredibly strong indirect exchange (RKKY) interaction even at significant separations above 1 nm. The results in this thesis highlight the rich array of phenomena that can manifest in two-dimensional materials and point towards potential future developments for atomic scale electronic and spintronic devices.

Type: Thesis (Doctoral)
Title: Modifying the electronic properties and magnetic interactions of the two-dimensional material silicene
Event: University College London (UCL)
Open access status: An open access version is available from UCL Discovery
Language: English
Keywords: two-dimensional, silicene, scanning tunneling microscopy, Kondo, RKKY
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: https://discovery.ucl.ac.uk/id/eprint/1532889
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