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Interaction phenomena in graphene seen through quantum capacitance |
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| Authors: | G. L. Yu R. Jalil Branson Belle Alexander S. Mayorov Peter Blake Frederick Schedin Sergey V. Morozov Leonid A. Ponomarenko F. Chiappini S. Wiedmann Uli Zeitler Mikhail I. Katsnelson A. K. Geim Kostya S. Novoselov Daniel C. Elias |
| Affiliation: | aSchool of Physics and Astronomy, and;bCentre for Mesoscience and Nanotechnology, University of Manchester, Manchester, M13 9PL, United Kingdom;;cInstitute for Microelectronics Technology, 142432 Chernogolovka, Russia;;dHigh Field Magnet Laboratory, Radboud University Nijmegen, NL-6525 ED Nijmegen, The Netherlands; and;eInstitute for Molecules and Materials, Radboud University Nijmegen, NL-6525 AJ Nijmegen, The Netherlands |
| Abstract: | Capacitance measurements provide a powerful means of probing the density of states. The technique has proved particularly successful in studying 2D electron systems, revealing a number of interesting many-body effects. Here, we use large-area high-quality graphene capacitors to study behavior of the density of states in this material in zero and high magnetic fields. Clear renormalization of the linear spectrum due to electron–electron interactions is observed in zero field. Quantizing fields lead to splitting of the spin- and valley-degenerate Landau levels into quartets separated by interaction-enhanced energy gaps. These many-body states exhibit negative compressibility but the compressibility returns to positive in ultrahigh B. The reentrant behavior is attributed to a competition between field-enhanced interactions and nascent fractional states. |
| Keywords: | Fermi velocity-renormalization boron nitride 2D based heterostructures |