Time-reversal invariant topological moiré flat band: A platform for the fractional quantum spin Hall effect

Wu, Yi-Ming; Shaffer, Daniel; Wu, Zhengzhi; Santos, Luiz H

doi:10.1103/PhysRevB.109.115111

This content will become publicly available on Wed Jan 01 00:00:00 EST 2025

Title: Time-reversal invariant topological moiré flat band: A platform for the fractional quantum spin Hall effect

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Abstract

Motivated by recent observation of the quantum spin Hall effect in monolayer germanene and twisted bilayer transition-metal-dichalcogenides (TMDs), we study the topological phases of moir twisted bilayers with time-reversal symmetry and spin sz conservation. By using a continuum model description which can be applied to both germanene and TMD bilayers, we show that at small twist angles the emergent moir flat bands can be topologically nontrivial due to inversion symmetry breaking. Each of these flat bands admits a lowest-Landau-level description for each spin projection in the chiral limit and at magic twist angle. This allows for the construction of a many-body Laughlin state with time-reversal symmetry which can be stabilized by a short-range pseudopotential, and therefore serves as an ideal platform for realizing the so-far elusive fractional quantum spin Hall effect with emergent spin-1/2 U(1) symmetry.

Authors:: Wu, Yi-Ming; Shaffer, Daniel; Wu, Zhengzhi; Santos, Luiz H

Publication Date:: Mon Jan 01 00:00:00 EST 2024

Research Org.:: Emory Univ., Atlanta, GA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 2317795

Grant/Contract Number:: SC0023327

Resource Type:: Accepted Manuscript

Journal Name:: Physical Review B

Additional Journal Information:: Journal Volume: 109; Journal Issue: 11; Journal ID: ISSN 2469--9950

Country of Publication:: United States

Language:: English

Subject:: 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

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                    Wu, Yi-Ming, Shaffer, Daniel, Wu, Zhengzhi, and Santos, Luiz H. Time-reversal invariant topological moiré flat band: A platform for the fractional quantum spin Hall effect.  United States: N. p., 2024. 
Web.  doi:10.1103/PhysRevB.109.115111.

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                    Wu, Yi-Ming, Shaffer, Daniel, Wu, Zhengzhi, & Santos, Luiz H. Time-reversal invariant topological moiré flat band: A platform for the fractional quantum spin Hall effect.  United States.  https://doi.org/10.1103/PhysRevB.109.115111

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                    Wu, Yi-Ming, Shaffer, Daniel, Wu, Zhengzhi, and Santos, Luiz H. Mon .  
"Time-reversal invariant topological moiré flat band: A platform for the fractional quantum spin Hall effect".  United States.  https://doi.org/10.1103/PhysRevB.109.115111.

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@article{osti_2317795,

  title        = {Time-reversal invariant topological moiré flat band: A platform for the fractional quantum spin Hall effect},

  author       = {Wu, Yi-Ming and Shaffer, Daniel and Wu, Zhengzhi and Santos, Luiz H},

  abstractNote = {Motivated by recent observation of the quantum spin Hall effect in monolayer germanene and twisted bilayer transition-metal-dichalcogenides (TMDs), we study the topological phases of moir twisted bilayers with time-reversal symmetry and spin sz conservation. By using a continuum model description which can be applied to both germanene and TMD bilayers, we show that at small twist angles the emergent moir flat bands can be topologically nontrivial due to inversion symmetry breaking. Each of these flat bands admits a lowest-Landau-level description for each spin projection in the chiral limit and at magic twist angle. This allows for the construction of a many-body Laughlin state with time-reversal symmetry which can be stabilized by a short-range pseudopotential, and therefore serves as an ideal platform for realizing the so-far elusive fractional quantum spin Hall effect with emergent spin-1/2 U(1) symmetry.},

  doi          = {10.1103/PhysRevB.109.115111},

  journal      = {Physical Review B},

  number       = 11,

  volume       = 109,

  place        = {United States},

  year         = {Mon Jan 01 00:00:00 EST 2024},

  month        = {Mon Jan 01 00:00:00 EST 2024}

}

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