Putting a new spin on the incommensurate Kekulé spiral: from spin-valley locking and collective modes to fermiology and implications for superconductivity
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arXiv
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| Autori principali: | , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866916950687350784 |
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| author | Wang, Ziwei Wagner, Glenn Kwan, Yves H. Bultinck, Nick Simon, Steven H. Parameswaran, S. A. |
| author_facet | Wang, Ziwei Wagner, Glenn Kwan, Yves H. Bultinck, Nick Simon, Steven H. Parameswaran, S. A. |
| contents | We revisit the global phase diagram of magic-angle twisted bilayer and [symmetric] trilayer graphene (MA-TBG/TSTG) in light of recent scanning tunneling microscopy (STM) measurements on these materials. These experiments both confirmed the importance of strain in stabilizing the predicted incommensurate Kekulé spiral (IKS) order near filling $|ν|=2$ of the weakly dispersive central bands in both systems, and suggested a key role for electron-phonon couplings and short-range Coulomb interactions in selecting between various competing orders at low strain in MA-TBG. Here, we show that such interactions $\textit{also}$ play a crucial role in selecting the spin structure of the strain-stabilized IKS state. This in turn influences the visibility of the IKS order in STM in a manner that allows us to infer their relative importance. We use this insight in conjunction with various other pieces of experimental data to build a more complete picture of the phase diagram, focusing on the spectrum of low-lying collective modes and the nature of the doped Fermi surfaces. We explore the broad phenomenological implications of these results for superconductivity. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_12320 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Putting a new spin on the incommensurate Kekulé spiral: from spin-valley locking and collective modes to fermiology and implications for superconductivity Wang, Ziwei Wagner, Glenn Kwan, Yves H. Bultinck, Nick Simon, Steven H. Parameswaran, S. A. Strongly Correlated Electrons Superconductivity We revisit the global phase diagram of magic-angle twisted bilayer and [symmetric] trilayer graphene (MA-TBG/TSTG) in light of recent scanning tunneling microscopy (STM) measurements on these materials. These experiments both confirmed the importance of strain in stabilizing the predicted incommensurate Kekulé spiral (IKS) order near filling $|ν|=2$ of the weakly dispersive central bands in both systems, and suggested a key role for electron-phonon couplings and short-range Coulomb interactions in selecting between various competing orders at low strain in MA-TBG. Here, we show that such interactions $\textit{also}$ play a crucial role in selecting the spin structure of the strain-stabilized IKS state. This in turn influences the visibility of the IKS order in STM in a manner that allows us to infer their relative importance. We use this insight in conjunction with various other pieces of experimental data to build a more complete picture of the phase diagram, focusing on the spectrum of low-lying collective modes and the nature of the doped Fermi surfaces. We explore the broad phenomenological implications of these results for superconductivity. |
| title | Putting a new spin on the incommensurate Kekulé spiral: from spin-valley locking and collective modes to fermiology and implications for superconductivity |
| topic | Strongly Correlated Electrons Superconductivity |
| url | https://arxiv.org/abs/2509.12320 |