Details

Autor(en) / Beteiligte

• Lee, Juwon
• Wong, Dillon
• Velasco Jr, Jairo
• Rodriguez-Nieva, Joaquin F.
• Kahn, Salman
• Tsai, Hsin-Zon
• Taniguchi, Takashi
• Watanabe, Kenji
• Zettl, Alex
• Wang, Feng
• Levitov, Leonid S.
• Crommie, Michael F.

Titel

Imaging electrostatically confined Dirac fermions in graphene quantum dots

Ist Teil von

• Nature physics, 2016-11, Vol.12 (11), p.1032-1036

Ort / Verlag

London: Nature Publishing Group

Erscheinungsjahr

2016

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Electrostatic confinement of charge carriers in graphene is governed by Klein tunnelling, a relativistic quantum process in which particle-hole transmutation leads to unusual anisotropic transmission at p-n junction boundaries1, 2, 3, 4, 5. Reflection and transmission at these boundaries affect the quantum interference of electronic waves, enabling the formation of novel quasi-bound states6, 7, 8, 9, 10, 11, 12. Here we report the use of scanning tunnelling microscopy to map the electronic structure of Dirac fermions confined in quantum dots defined by circular graphene p-n junctions. The quantum dots were fabricated using a technique involving local manipulation of defect charge within the insulating substrate beneath a graphene monolayer13. Inside such graphene quantum dots we observe resonances due to quasi-bound states and directly visualize the quantum interference patterns arising from these states. Outside the quantum dots Dirac fermions exhibit Friedel oscillation-like behaviour. Bolstered by a theoretical model describing relativistic particles in a harmonic oscillator potential, our findings yield insights into the spatial behaviour of electrostatically confined Dirac fermions.