Journal Article

Electronic phase separation in multilayer rhombohedral graphite

Xu, Shuigang, Taniguchi, Takashi, Novoselov, Kostya S., Ozdemir, Servet, Fal’ko, Vladimir I., Yang, Yaping, Mullan, Ciaran, Barrier, Julien, Berdyugin, Alexey I., Slizovskiy, Sergey, Geim, A. K., Shi, Yanmeng, Yin, Jun, Son, Seok-Kyun, Watanabe, Kenji, Piot, Benjamin A., Mishchenko, Artem, Morozov, Sergey V.

2020

Overview

Of the two stable forms of graphite, hexagonal and rhombohedral, the former is more common and has been studied extensively. The latter is less stable, which has so far precluded its detailed investigation, despite many theoretical predictions about the abundance of exotic interaction-induced physics 1 – 6 . Advances in van der Waals heterostructure technology 7 have now allowed us to make high-quality rhombohedral graphite films up to 50 graphene layers thick and study their transport properties. Here we show that the bulk electronic states in such rhombohedral graphite are gapped 8 and, at low temperatures, electron transport is dominated by surface states. Because of their proposed topological nature, the surface states are of sufficiently high quality to observe the quantum Hall effect, whereby rhombohedral graphite exhibits phase transitions between a gapless semimetallic phase and a gapped quantum spin Hall phase with giant Berry curvature. We find that an energy gap can also be opened in the surface states by breaking their inversion symmetry by applying a perpendicular electric field. Moreover, in rhombohedral graphite thinner than four nanometres, a gap is present even without an external electric field. This spontaneous gap opening shows pronounced hysteresis and other signatures characteristic of electronic phase separation, which we attribute to emergence of strongly correlated electronic surface states. High-quality rhombohedral graphite films are found to offer an alternative to twisted bilayer graphene as a platform for studying correlated physics in carbon materials.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 140/133 / 142/126 / 639/766/119/2794 / 639/766/119/2795 / 639/766/119/544 / 639/766/119/995 / Asymmetry / Chemical properties / Condensed Matter / Electric fields / Electric properties / Electromagnetism / Electron states / Electron transport / Energy gap / Graphene / Graphite / Hall effect / Heterostructures / Humanities and Social Sciences / Low temperature / Magnetic fields / Mesoscopic Systems and Quantum Hall Effect / multidisciplinary / Multilayers / Phase separation / Phase transitions / Physics / Quality / Quantum Hall effect / Science / Science (multidisciplinary) / Spectrum analysis / Symmetry / Transport properties