Chen, Chaoyu http://orcid.org/0000-0002-3930-8294
Avila, José
Arezki, Hakim
Nguyen, Van Luan
Shen, Jiahong
Mucha-Kruczyński, Marcin
Yao, Fei
Boutchich, Mohamed
Chen, Yue
Lee, Young Hee http://orcid.org/0000-0001-7403-8157
Asensio, Maria C.
Article History
Received: 27 April 2016
Accepted: 6 March 2018
First Online: 9 April 2018
Change Date: 27 September 2018
Change Type: Correction
Change Details: The authors unanimously wish to retract this Article due to their concerns about the interpretation of the low-energy electron microscopy (LEEM) and diffraction (LEED) patterns reported in the manuscript. In this study, the authors used spatial and angle-resolved photoemission spectroscopy (ARPES) to characterize graphene monolayers grown on copper foils, and observed regions of graphene adlayers with enhanced graphene/Cu interaction, higher Dirac cone doping level, moiré mini Dirac cones and large lattice expansion. All these properties have been clearly verified and reproduced by photoemission spectroscopy as well as explained by density functional theory. LEEM and LEED characterization were also carried out to confirm the existence of a moiré superlattice and lattice expansion, and the results were included in the main manuscript and Supplementary Information. On further analysis of the LEEM/LEED data, it seems that while the existence of a moiré superlattice can be corroborated, the conclusion of graphene lattice expansion (7%) based on spatially resolved ARPES determinations cannot be confirmed by the LEEM/LEED measurements. The authors realized that these measurements were collected from statistically non-representative areas of the sample. Moreover, the fact that the raw microLEED images bear an asymmetry factor of as much as 5% due to the instrumental aberration makes it impossible to estimate any compression or expansion of the same order. Consequently, their conclusion on the graphene lattice expansion can only be supported by the photoemission data. In view that more complete and reliable structural determinations should be conducted, all authors wish to retract this Article.
Competing interests
: The authors declare no competing interests.