| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Thin Films | Tuesday Sessions |
| Session TF-TuP |
| Session: | Thin Films Poster Session |
| Presenter: | Satoshi Moriyama, National Institute for Materials Science, Japan |
| Authors: | S. Moriyama, National Institute for Materials Science, Japan Y. Morita, Gunma University, Japan E. Watanabe, National Institute for Materials Science, Japan D. Tsuya, National Institute for Materials Science, Japan |
| Correspondent: | Click to Email |
Field-induced Confinement and Quantum Transport in Graphene
Satoshi Moriyama1,*, Yoshifumi Morita2, Eiichiro Watanabe3, Daiju Tsuya3
1 International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS),
1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
2 Faculty of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan.
3 Nanotechnology Innovation Station, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
MORIYAMA.Satoshi@nims.go.jp [mailto:MORIYAMA.Satoshi@nims.go.jp]
Graphene consists of a single atomic layer of carbon atoms and has provided a new stage for studying low dimensional physics. The corresponding energy dispersion adopts the so-called Dirac cone, which leads to a massless Dirac-particle and relativistic quantum physics in a condensed matter. From the application point of view, the ballistic transport and high mobility in graphene make them possible candidates for future nanodevices, such as integrated quantum-dot (QD) devices. However, confining massless Dirac fermions in graphene is difficult due to Klein tunneling and the zero-band-gap electronic structure. Therefore, although attempts have been made to design graphene QD devices, they often suffer from severe design limitations. They basically consist of small QD islands, which confine electrons geometrically, to which narrow graphene-constrictions are connected. We have also demonstrated double QD devices, which exhibits single-electron transport of two lateral QDs coupled in series [1]. In this case, the device performance has been limited due to detailed constriction and edge orientation. It is crucially important to develop other methods of creating graphene nanostructures and control the constrictions.
In this paper, we report an alternative approach to confine the massless carriers in graphene, in which graphene mesoscopic structures are perfectly isolated and metallic contacts are directly deposited onto them without constrictions. We show an experimental demonstration of a magnetic-field-induced quantum confinement in the graphene device. There are several theoretical scenarios for field-induced confinement of massless Dirac fermions, such as the confinement by inhomogeneous magnetic fields. Here, the confinement in our device is induced by both a uniform magnetic field perpendicular to the graphene sheet and an electrostatic surface-potential formed by the metal/graphene junction. Our experimental results indicate that a quantum confinement–deconfinement transition is controlled by the magnetic field [2].
[1] S. Moriyama et al., Nano Lett. 9, 2891 (2009).
[2] S. Moriyama et al., Appl. Phys. Lett. 104, 053108 (2014).