Home > Research Teams > Surfaces, Interfaces, Molecules & 2D Materials (SIM2D) > Graphene : Molecules & Transport
STM topography and I(V), I(Z) and Z(V) spectroscopies are used to study the atomic-scale structural, electronic and electron transport properties of graphene epitaxially grown on SiC substrates. STM is also used to investigate self-assembling and reactivity of molecules on graphene with the aim to locally modify the electronic properties of graphene.
Techniques: Room temperature STM - STS, UHV, molecular deposition
![]() Leader: Andrew Mayne Participants: Hamid Oughaddou, Hanna Enriquez, Philippe Roncin, Gérald Dujardin Student: Nian Jheng Wu Past Contributors: Mali Zhao, Laury Martins-Lopès, Heejun Yang & Geneviève Comtet STM topography and I(V), I(Z) and Z(V) spectroscopies are used to study the atomic-scale structural, electronic and electron transport properties of graphene epitaxially grown on SiC substrates. STM is also used to investigate self-assembling and reactivity of molecules on graphene with the aim to locally modify the electronic properties of graphene. |
Techniques: Room temperature STM - STS, UHV, molecular deposition
Highlights
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article: F. Shao, S. Y. Woo, N. J. Wu, R. Schneider, A. J. Mayne, S. Michaelis de Vasconcellos, A. Arora, B. J. Carey, J. A. Preuß, N. Bonnet, M. Och, C. Mattevi, K. Watanabe, T. Taniguchi, Z. Niu, R. Bratschitsch, and L. H. G. Tizei, “Substrate influence on transition metal dichalcogenide monolayer exciton absorption linewidth broadening” Physical Review Materials 6, 074005 (2022)
Detection of graphene’s divergent orbital diamagnetism at the Dirac point. The electronic properties of graphene have been intensively investigated over the past decade. However, the singular orbital magnetism of undoped graphene, a fundamental signature of the characteristic Berry phase of graphene’s electronic wave functions, has been challenging to measure in a single flake. Using a highly sensitive giant magnetoresistance (GMR) sensor, we have measured the gate voltage–dependent magnetization of a single graphene monolayer encapsulated between boron nitride crystals. The signal exhibits a diamagnetic peak at the Dirac point whose magnetic field and temperature dependences agree with long-standing theoretical predictions. Our measurements offer a means to monitor Berry phase singularities and explore correlated states generated by the combined effects of Coulomb interactions, strain, or moiré potentials.
article: J. Vallejo Bustamante, N.-J. Wu , C. Fermon, M. Pannetier-Lecoeur, T. Wakamura, K. Watanabe, T. Taniguchi, T. Pellegrin, A. Bernard, S. Daddinounou, V. Bouchiat, S. Guéron, M. Ferrier, G. Montambaux, and H. Bouchiat, “Detection of graphene’s divergent orbital diamagnetism at the Dirac point” Science 374, 1399-1402 (2021)
Spin-Orbit-Enhanced Robustness of Supercurrent in Graphene/WS2 Josephson Junctions. We demonstrate the enhanced robustness of the supercurrent through graphene-based Josephson junctions in which strong spin-orbit interactions (SOIs) are induced. We compare the persistence of a supercurrent at high out-of-plane magnetic fields between Josephson junctions with graphene on hexagonal boron-nitride and graphene on WS2, where strong SOIs are induced via the proximity effect. We find that in the shortest junctions both systems display signatures of induced superconductivity, characterized by a suppressed differential resistance at a low current, in magnetic fields up to 1 T. In longer junctions, however, only graphene on WS2 exhibits induced superconductivity features in such high magnetic fields, and they even persist up to 7 T. We argue that these robust superconducting signatures arise from quasiballistic edge states stabilized by the strong SOIs induced in graphene by WS2.
article: T. Wakamura, N.-J. Wu , A. D. Chepelianskii, S. Guéron, M. Och, M. Ferrier, T. Taniguchi, K. Watanabe, C. Mattevi, and H. Bouchiat, “Spin-Orbit-Enhanced Robustness of Supercurrent in Graphene/WS2 Josephson Junctions” Phys. Rev. Lett. 125, 266801 (2020)
Sub-molecular spectroscopy and temporary molecular charging of Ni-Phthalocyanine on graphene by STM. In this study, the self-assembled molecular network and electronic properties of Ni-phthalocyanine (NiPc) molecules on monolayer graphene (MLG)/6H-SiC(0001) were studied by room temperature Scanning Tunnelling Microscopy (STM) and Density Functional Theory (DFT) calculations. In this study, a very weak electronic coupling between the graphene and the NiPc molecules is found. This is due to the very small charge transfer of only 0.035e- per molecule. The weak molecule–graphene interaction has two observable consequences : sub-molecular resolution was obtained in the STM spectroscopy at room-temperature with the molecules adsorbed directly on the graphene, and the occupied and unoccupied molecular resonance peaks were observed to shift their position in energy as a function of the tip–surface distance. This is due to the temporary local charging (either positive or negative) that is achieved by decreasing the surface voltage under the STM tip. This may have important consequences for future studies of the opto-electronic properties of such hybrid graphene–molecule systems.
article: M. Zhao, F. Al Marzouqi, E. Duverger, Ph. Sonnet, G. Dujardin, A.J. Mayne, “Sub-molecular spectroscopy and temporary molecular charging of Ni-Phthalocyanine on graphene by STM” Phys. Chem. Chem. Phys. 20, 19507 (2018)
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article: M. Debiossac, A. Zugarramurdi, Z. Mu, P. Lunca-Popa, A.J. Mayne, P. Roncin, "Helium diffraction on SiC grown graphene, qualitative and quantitative description with the hard corrugated wall model”, Phys. Rev. B 94, 205403 (2016)
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article : A. Zugarramurdi, M. Debiossac, P. Lunca-Popa, A. J. Mayne, A. Momeni, A. G. Borisov, Z. Mu, P. Roncin, H. Khemliche, "Determination of the geometric corrugation of graphene on SiC(0001) by grazing incidence fast atom diffraction", Appl. Phys. Lett. 106, 101902 (2015)
Fluorescence Lifetime and Blinking of Individual Semiconductor Nanocrystals on Graphene. A new class of optoelectronic nanodevices consisting of 0D semiconductor nanocrystals and 2D single graphene layers may be used to investigate and control the transfer of energy and charge in low-dimensional systems. The fluorescence dynamics of individual colloidal quantum dots (QDs) on graphene are investigated on both the nanosecond time scale (fluorescence lifetime) and the 1−100 s time scale (blinking statistics). We find that (i) a nonradiative energy transfer rate of ≈5 × 10+8 s−1 from the reduced lifetimes of QDs on graphene ; (ii) QDs still exhibit fluorescence intermittency (“blinking”) on graphene ; (iii) QD coupling to graphene increases the “on” state residence time ; and (iv) the QD fluorescence emission spectrum is unaltered by the QD−graphene coupling.
article : B. Rogez, H. Yang, E. Le Moal, S. Lévêque-Fort, E. Boer-Duchemin, F. Yao, Y.-H. Lee, Y. Zhang, D. Wegner, N. Hildebrandt, A. Mayne, G. Dujardin, “Fluorescence lifetime and blinking of individual semiconductor nanocrystals on graphene”, J. Phys. Chem. C 118, 18445 (2014)
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article : H. Yang, C. Cejas, A.J. Mayne, G. Dujardin, Y. Kuk, "Manipulation at a distance : Atomic scale observation of ballistic electron transport in single layer graphene", Appl. Phys. Lett. 102, 223104 (2013)
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Article: H. Yang, A.J. Mayne, G. Comtet, G. Dujardin, Y. Kuk, L. Stauffer, Ph. Sonnet, S. Nagarajan, A. Gourdon, "STM imaging, spectroscopy & manipulation of a self-assembled PTCDI monolayer on epitaxial graphene", Phys. Chem. Chem. Phys. 15, 4939 (2013)
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Article: H. Yang, A.J. Mayne, M. Boucherit, G. Comtet, G. Dujardin, Y. Kuk, "Quantum Interference Channeling at Graphene Edges", Nano Letters 10, 943 (2010)