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Twisted double bilayer graphene band topology

Published on:

18 March 2024

Primary Category:

Mesoscale and Nanoscale Physics

Paper Authors:

Kamalesh Bera,

Priyanka Mohan,

Arijit Saha

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Key Details

tDBLG transitions from valley Hall insulator to quantum spin Hall insulator with spin-orbit coupling

Direct band gap closings indicate topological phase transitions in tDBLG

Increasing SOC strength pushes topological phases to higher twist angles and gate voltages

Twisting DBLG creates distinct topological phases compared to untwisted case

Combining twist angle, SOC, and electric field enables diverse topological phases

AI generated summary

Twisted double bilayer graphene band topology

This paper theoretically investigates topological phase transitions in small-angle twisted double bilayer graphene (tDBLG) under a gate voltage and intrinsic spin-orbit coupling (SOC). Using a continuum model, the authors analyze band structure, direct band gap closings, and Chern numbers. Without SOC, tDBLG acts as a valley Hall insulator, but with SOC, it transitions to a quantum spin Hall insulator, gaining band topology in previously non-topological parameter spaces. Comparisons to untwisted DBLG reveal distinct topological phases from twisting. Overall, the interplay between twist angle, SOC, and electric field tunes tDBLG's diverse topological band properties.

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