Mechanically controlled quantum interference in graphene break junctions

Mechanically controlled quantum interference in graphene break junctions

Caneva, S. (TU Delft QN/van der Zant Lab; Kavli institute of nanoscience Delft)
Gehring, P. (TU Delft QN/van der Zant Lab; Kavli institute of nanoscience Delft)
García-Suárez, Víctor M. (Universidad de Oviedo)
García-Fuente, Amador (Universidad de Oviedo)
Stefani, D. (TU Delft QN/van der Zant Lab; Kavli institute of nanoscience Delft)
Olavarria Contreras, I.J. (TU Delft QN/van der Zant Lab; Kavli institute of nanoscience Delft)
Ferrer, Jaime (Universidad de Oviedo)
Dekker, C. (TU Delft BN/Cees Dekker Lab; Kavli institute of nanoscience Delft)
van der Zant, H.S.J. (TU Delft QN/van der Zant Lab; Kavli institute of nanoscience Delft)

2018

The ability to detect and distinguish quantum interference signatures is important for both fundamental research and for the realization of devices such as electron resonators¹, interferometers² and interference-based spin filters³. Consistent with the principles of subwavelength optics, the wave nature of electrons can give rise to various types of interference effects⁴, such as Fabry–Pérot resonances⁵, Fano resonances⁶ and the Aharonov–Bohm effect⁷. Quantum interference conductance oscillations⁸ have, indeed, been predicted for multiwall carbon nanotube shuttles and telescopes, and arise from atomic-scale displacements between the inner and outer tubes^9,10. Previous theoretical work on graphene bilayers indicates that these systems may display similar interference features as a function of the relative position of the two sheets^11,12. Experimental verification is, however, still lacking. Graphene nanoconstrictions represent an ideal model system to study quantum transport phenomena^13–15 due to the electronic coherence¹⁶ and the transverse confinement of the carriers¹⁷. Here, we demonstrate the fabrication of bowtie-shaped nanoconstrictions with mechanically controlled break junctions made from a single layer of graphene. Their electrical conductance displays pronounced oscillations at room temperature, with amplitudes that modulate over an order of magnitude as a function of subnanometre displacements. Surprisingly, the oscillations exhibit a period larger than the graphene lattice constant. Charge-transport calculations show that the periodicity originates from a combination of the quantum interference and lattice commensuration effects of two graphene layers that slide across each other. Our results provide direct experimental observation of a Fabry–Pérot-like interference of electron waves that are partially reflected and/or transmitted at the edges of the graphene bilayer overlap region.

http://resolver.tudelft.nl/uuid:672becb4-2637-44f4-8be0-8d584848ad0b

https://doi.org/10.1038/s41565-018-0258-0

2018-03-17

1748-3387

Nature Nanotechnology, 1126-1131

Accepted Author Manuscript

Institutional Repository

journal article

© 2018 S. Caneva, P. Gehring, Víctor M. García-Suárez, Amador García-Fuente, D. Stefani, I.J. Olavarria Contreras, Jaime Ferrer, C. Dekker, H.S.J. van der Zant