Quantum parity Hall effect in Bernal-stacked trilayer graphene

Journal Article · Fri May 03 00:00:00 EDT 2019 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.1820835116· OSTI ID:1510559

Stepanov, Petr; Barlas, Yafis; Che, Shi; Myhro, Kevin; Voigt, Greyson; Pi, Ziqi; Watanabe, Kenji ; Taniguchi, Takashi; Smirnov, Dmitry; Zhang, Fan; Lake, Roger K.; MacDonald, Allan H.; Lau, Chun Ning

The quantum Hall effect has recently been generalized from transport of conserved charges to include transport of other approximately conserved-state variables, including spin and valley, via spin- or valley-polarized boundary states with different chiralities. In this paper, we report a class of quantum Hall effect in Bernal- or ABA-stacked trilayer graphene (TLG), the quantum parity Hall (QPH) effect, in which boundary channels are distinguished by even or odd parity under the system’s mirror reflection symmetry. At the charge neutrality point, the longitudinal conductance ${\sigma }_{xx}$ is first quantized to $4e^2/h$at a small perpendicular magnetic field $B_{\perp }$, establishing the presence of four edge channels. As $B_{\perp }$increases, ${\sigma }_{xx}$ first decreases to $2e^2/h$, indicating spin-polarized counterpropagating edge states, and then, to approximately zero. These behaviors arise from level crossings between even- and odd-parity bulk Landau levels driven by exchange interactions with the underlying Fermi sea, which favor an ordinary insulator ground state in the strong $B_{\perp }$ limit and a spin-polarized state at intermediate fields. The transitions between spin-polarized and -unpolarized states can be tuned by varying Zeeman energy. Our findings demonstrate a topological phase that is protected by a gate-controllable symmetry and sensitive to Coulomb interactions.

• Research Organization: Univ. of Texas, Austin, TX (United States); Univ. of California, Riverside, CA (United States); Energy Frontier Research Centers (EFRC) (United States). Spins and Heat in Nanoscale Electronic Systems (SHINES)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Science Foundation (NSF); State of Florida; Ministry of Education, Culture, Sports, Science and Technology (MEXT); Japan Society for the Promotion of Science (JSPS); Welch Foundation; US Army Research Office (ARO)
• Grant/Contract Number: FG03-02ER45958; SC0010597; SC0012670; F1473; W911NF-18-1-0416
• OSTI ID: 1510559
• Alternate ID(s): OSTI ID: 1614570
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 116 Journal Issue: 21; ISSN 0027-8424
• Publisher: National Academy of Sciences
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Science & technology - other topics
2D materials
quantum Hall effect
topological insulators
symmetry-protected phases
trilayer graphene