Transporte eletrônico por estados topológicos em grafeno bicamada dobrado: uma plataforma para a valetrônica

Abstract

Valetronics is an emergent field on electronics that manipulates the valley number, a degree of freedom similar to the electron spin, to develop faster and more efficient devices with low power consumption. The development of valleytronics demands long-range electronic transport with preserved valley index. A promising structure to this end is a topological one-dimensional (1D) channel formed in bilayer graphene (BLG) called domain wall (DW). In these 1D channels, the valley-index defines the propagation direction of the charge carriers and the chiral edge states (kink states) are robust over many kinds of disorder. However, the fabrication of DWs is challenging, requiring the design of complex multi-gate structures with nanometer alignment or have been producing on rough substrates, showing a limited mean free path. In our work, we create a new structure to form a high-quality domain walls. Such structure is formed along the curved boundary of a folded bilayer graphene. Our investigation of the ballistic transport at such nano-width channel with two terminal measurements reveal the resistance quantization by the quantum value of R = h 4e2 at zero-magnetic fields. The four probe experiments show a collapse of the longitudinal resistance, the expected resistance of a ballistic channel. We also demonstrate the metallic behavior of the topologically protected one dimensional states by performing measurements as function of the temperature and we showed that the ballistic transmission of valley protected states was achieved for long mean-free paths. At the bulk, we measure an semiconducting behavior with tunable bandgap. We envision that such new valleytronic platform could either be exploited for studies of Luttinger liquids behaviors or for the development of dissipationless electronic quantum wires and development of electronic valley valves.