Project title: Periodically strained graphene; structural and electronic properties – PERSTAGRA
Project No. : IP-11-2013- 2727
Funding agency: Croatian Science Foundation (HRZZ)
Project leader: Petar Pervan
Funding: 366.000 HR Kuna
Duration: 01. Junly 2014 – 30. June 2016.
Institution: Institut za fiziku, Zagreb, Croatia
Project team: Iva Šrut Rakić, Vesna Mikšić Trontl, Ivo Pletikosić (Princeton University USA), Tonica Valla (Brookhaven national Laboratory USA), Maria Asensio (SOLEIL Synchrotron, Paris, France)
A strained graphene offers a valuable avenue for the manipulation in altering its electronic structure. Graphene can withstand rather large elastic deformation and it appears that within the elastic response there is a range of different modifications in graphene’s electronic structure. This is a basis of what is called “strain engineering”. Recent theoretical calculations suggest that uniaxial strain or shear deformations can induce opening of the electron band gap, anisotropic modification of the Fermi velocity and consequently alter the transport properties. However, there is still no consensus on the mechanical conditions required to obtain a particular electronic modification.
In this project we propose a systematic study of structural and electronic properties of periodically rippled graphene. We have already demonstrated that graphene conforms to the stepped (vicinal) iridium surface – Ir(332) creating periodic structure at nanometer scale. It is aim of this project to experimentally explore the dependence of the electronic structure of graphene with respect to periodicity of the graphene corrugation, orientation of the graphene with respect to the shear deformation (zig-zag with respect to armchair direction). By intercalation of different elements we will try to alter the graphene substrate interaction with the aim to control the structure of the underlying surface and consequently valence band structure of graphene.
We shall investigate structural properties of graphene on Ir(332) by Scanning Tunnelling Microscope (STM) and Atomic Force Microscope (AFM). The focus in the investigation of electronic properties will be on the ARPES study of anisotropic distortion of the Dirac cone, relation with the direction of the graphene modulation, spin-orbit interaction and on the possibility to induce electron band gap.