부산대학교 도서관

Insights into the fundamental properties of graphene's Dirac-Weyl fermions have emerged from studies of electron tunnelling transistors in which an atomically thin layer of hexagonal boron nitride (hBN) is sandwiched between two layers of high purity graphene. Here, we show that when a single defect is present within the hBN tunnel barrier, it can inject electrons into the graphene layers and its sharply defined energy level acts as a high resolution spectroscopic probe of electron-electron interactions in graphene. We report a magnetic field dependent suppression of the tunnel current flowing through a single defect below temperatures of ~2 K. This is attributed to the formation of a magnetically-induced Coulomb gap in the spectral density of electrons tunnelling into graphene due to electron-electron interactions. Electron-electron interactions are known to play an important role in the in-plane transport properties of graphene-based devices. Here, the authors investigate the role of electron-electron interactions on electrons tunnelling between the layers of a graphene/hBN/graphene tunnel transistor and demonstrate the emergence of a Coulomb gap at low temperatures and in quantising magnetic fields. [ABSTRACT FROM AUTHOR]