High-Mobility Compensated Semimetals, Orbital Magnetization, and Umklapp Scattering in Bilayer Graphene Moiré Superlattices

High-Mobility Compensated Semimetals, Orbital Magnetization, and Umklapp Scattering in Bilayer Graphene Moiré Superlattices

ACS Nano

10.1021/acsnano.3c13212

https://doi.org/10.1021/acsnano.3c13212

Artur L. Shilov, Mikhail A. Kashchenko, Pierre A. Pantaleón Peralta, Yibo Wang, Mikhail Kravtsov, Andrei Kudriashov, Zhen Zhan, Takashi Taniguchi, Kenji Watanabe, Sergey Slizovskiy, Kostya S. Novoselov, Vladimir I. Fal’ko, Francisco Guinea, Denis A. Bandurin

22 April 2024

Shilov, A. L., Kashchenko, M. A., Pantaleón Peralta, P. A., Wang, Y., Kravtsov, M., Kudriashov, A., Zhan, Z., Taniguchi, T., Watanabe, K., Slizovskiy, S., Novoselov, K. S., Fal’ko, V. I., Guinea, F., & Bandurin, D. A. (2024). High-Mobility Compensated Semimetals, Orbital Magnetization, and Umklapp Scattering in Bilayer Graphene Moiré Superlattices. ACS Nano, 18(18), 11769–11777. https://doi.org/10.1021/acsnano.3c13212

Twist-controlled moiré superlattices (MSs) have emerged as a versatile platform for realizing artificial systems with complex electronic spectra. The combination of Bernal- stacked bilayer graphene (BLG) and hexagonal boron nitride (hBN) can give rise to an interesting MS, which has recently featured a set of unexpected behaviors, such as unconventional ferroelectricity and the electronic ratchet effect. Yet, the understanding of the electronic properties of BLG/hBN MS has, at present, remained fairly limited. Here, we combine magneto-transport and low-energy sub-THz excitation to gain insightsintothepropertiesofthisMS.Wedemonstratethatthe alignment between BLG and hBN crystal lattices results in the emergence of compensated semimetals at some integer fillings of the moiré bands, separated by van Hove singularities where the Lifshitz transition occurs. A particularly pronounced semimetal develops when eight holes reside in the moiré unit cell, where coexisting high-mobility electron and hole systems feature strong magnetoresistance reaching 2350% already at B= 0.25 T. Next, by measuring the THz-driven Nernst effect in remote bands, we observe valley splitting, indicating an orbital magnetization characterized by a strongly enhanced effective gv-factor of 340. Finally, using THz photoresistance measurements, we show that the high-temperature conductivity of the BLG/hBN MS is limited by electron−electron umklapp processes. Our multifaceted analysis introduces THz-driven magnetotransport as a convenient tool to probe the band structure and interaction effects in van der Waals materials and provides a comprehensive understanding of the BLG/hBN MS.

Publisher Copyright

This research / project is supported by the Agency for Science, Technology and Research - Young Individual Research Grant
Grant Reference no. : M22K3c0106

This research / project is supported by the Ministry of Education, Singapore - Academic Research Fund Tier 2
Grant Reference no. : T2EP50123-0020

This research / project is supported by the Ministry of Education, Singapore - Research Centre of Excellence award to the Institute for Functional Intelligent Materials, I-FIM
Grant Reference no. : EDUNC-33-18-279- V12

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see 10.1021/acsnano.3c13212

https://oar.a-star.edu.sg/communities-collections/articles/21899

1936-0851
1936-086X

Science and Engineering Research Council