More than a decade after the discovery of graphene, ballistic transport in nanostructures based on this intriguing material still represents a challenging field of research in two-dimensional electronics. The presence of rough edges in nanostructures based on this material prevents the appearance of truly ballistic electron transport as theo\-re\-tically predicted and, therefore, not well-developed plateaus of conductance have been revealed to date. In this work we report on a novel implementation of the cryo-etching method, which enabled us to fabricate graphene nanoconstrictions encapsulated between hexagonal boron nitride thin films with unprecedented control of the structure edges. High quality smooth nanometer-rough edges are characterized by atomic force microscopy and a clear correlation between low roughness and the existence of well-developed quantized conductance steps with the concomitant occurrence of ballistic transport is found at low temperature. In par\-ti\-cu\-lar, we come upon exact 2e2/h quantization steps of conductance at zero magnetic field due to size quantization, as it has been theoretically predicted for truly ballistic electron transport through graphene nanoconstrictions.
@article{arxiv.1902.07459,
title = {Quantum nanoconstrictions fabricated by cryo-etching in encapsulated graphene},
author = {Vito Clericò and Juan Antonio Delgado-Notario and Marta Saiz-Bretín and Andrey V. Malyshev and Yahya M. Meziani and Pedro Hidalgo and Bianchi Méndez and Mario Amado and Francisco Domínguez-Adame and Enrique Diez},
journal= {arXiv preprint arXiv:1902.07459},
year = {2019}
}