Universität zu Köln

Hell, Martin G., Ehlen, Niels, Senkovskiy, Boris V., Hasdeo, Eddwi H., Fedorov, Alexander, Dombrowski, Daniela, Busse, Carsten, Michely, Thomas, di Santo, Giovanni, Petaccia, Luca, Saito, Riichiro and Grüneis, Alexander (2018). Resonance Raman spectrum of doped epitaxial graphene at the Lifshitz transition. Nano letters. ACS Publications. ISSN 1530-6992

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Abstract

We employ ultra-high vacuum (UHV) Raman spectroscopy in tandem with angle-resolved photoemission (ARPES) to investigate the doping-dependent Raman spectrum of epitaxial graphene on Ir(111). The evolution of Raman spectra from pristine to heavily Cs doped graphene up to a carrier concentration of 4.4*10^14cm^-2 is investigated. At this doping graphene is at the onset of the Lifshitz transition and renormalization effects reduce the electronic bandwidth. The optical transition at the saddle point in the Brillouin zone then becomes experimentally accessible by ultraviolet (UV) light excitation which achieves resonance Raman conditions in close vicinity to the van Hove singularity in the joint density of states. The position of the Raman G band of fully doped graphene/Ir(111) shifts down by ~60cm^-1. The G band asymmetry of Cs doped epitaxial graphene assumes an unusual strong Fano asymmetry opposite to that of the G band of doped graphene on insulators. Our calculations can fully explain these observations by substrate dependent quantum interference effects in the scattering pathways for vibrational and electronic Raman scattering.

Item Type:	Article
Creators:	Creators Email ORCID ORCID Put Code Hell, Martin G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ehlen, Niels UNSPECIFIED UNSPECIFIED UNSPECIFIED Senkovskiy, Boris V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hasdeo, Eddwi H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fedorov, Alexander UNSPECIFIED UNSPECIFIED UNSPECIFIED Dombrowski, Daniela UNSPECIFIED UNSPECIFIED UNSPECIFIED Busse, Carsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Michely, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED di Santo, Giovanni UNSPECIFIED UNSPECIFIED UNSPECIFIED Petaccia, Luca UNSPECIFIED UNSPECIFIED UNSPECIFIED Saito, Riichiro UNSPECIFIED UNSPECIFIED UNSPECIFIED Grüneis, Alexander UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-85617
Identification Number:	10.1021/acs.nanolett.8b02979
Journal or Publication Title:	Nano letters
Date:	29 August 2018
Publisher:	ACS Publications
ISSN:	1530-6992
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics II
Subjects:	Physics
Funders:	ERC grant no. 648589 ’SUPER-2D’, INST 216/808- 1 FUGG, “Quantum Matter and Materials” (QM2) initiative, Horizon 2020 EC programme under grant agreement n. 730872 (CALIPSOplus), MEXT KAKENHI (Nos. JPI8H01810, JP15K21722)
Projects:	DFG project A01 with CRC 1238 and GR 3708/2-1
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/8561