Landau-Level Mixing and SU(4) Symmetry Breaking in Graphene
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arXiv
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| Autores principales: | , , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866909080532025344 |
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| author | Wei, Nemin Xu, Guopeng Villadiego, Inti Sodemann Huang, Chunli |
| author_facet | Wei, Nemin Xu, Guopeng Villadiego, Inti Sodemann Huang, Chunli |
| contents | Recent scanning tunneling microscopy experiments on graphene at charge neutrality under strong magnetic fields have uncovered a ground state characterized by Kekulé distortion (KD). In contrast, non-local spin and charge transport experiments in double-encapsulated graphene, which has a higher dielectric constant, have identified an antiferromagnetic (AF) ground state. We propose a mechanism to reconcile these conflicting observations, by showing that Landau-level mixing can drive a transition from AF to KD with the reduction of the dielectric screening. Our conclusion is drawn from studying the effect of Landau-level mixing on the lattice-scale, valley-dependent interactions to leading order in graphene's fine structure constant $κ= e^2/(\hbar v_F ε)$. This analysis provides three key insights: 1) Valley-dependent interactions remain predominantly short-range with the $m=0$ Haldane pseudopotential being at least an order of magnitude greater than the others, affirming the validity of delta-function approximation for these interactions. 2) The phase transition between the AF and KD states is driven by the microscopic process in the double-exchange Feynman diagram. 3) The magnitudes of the coupling constants are significantly boosted by remote Landau levels. Our model also provides a theoretical basis for numerical studies of fractional quantum Hall states in graphene. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_12528 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Landau-Level Mixing and SU(4) Symmetry Breaking in Graphene Wei, Nemin Xu, Guopeng Villadiego, Inti Sodemann Huang, Chunli Mesoscale and Nanoscale Physics Strongly Correlated Electrons Recent scanning tunneling microscopy experiments on graphene at charge neutrality under strong magnetic fields have uncovered a ground state characterized by Kekulé distortion (KD). In contrast, non-local spin and charge transport experiments in double-encapsulated graphene, which has a higher dielectric constant, have identified an antiferromagnetic (AF) ground state. We propose a mechanism to reconcile these conflicting observations, by showing that Landau-level mixing can drive a transition from AF to KD with the reduction of the dielectric screening. Our conclusion is drawn from studying the effect of Landau-level mixing on the lattice-scale, valley-dependent interactions to leading order in graphene's fine structure constant $κ= e^2/(\hbar v_F ε)$. This analysis provides three key insights: 1) Valley-dependent interactions remain predominantly short-range with the $m=0$ Haldane pseudopotential being at least an order of magnitude greater than the others, affirming the validity of delta-function approximation for these interactions. 2) The phase transition between the AF and KD states is driven by the microscopic process in the double-exchange Feynman diagram. 3) The magnitudes of the coupling constants are significantly boosted by remote Landau levels. Our model also provides a theoretical basis for numerical studies of fractional quantum Hall states in graphene. |
| title | Landau-Level Mixing and SU(4) Symmetry Breaking in Graphene |
| topic | Mesoscale and Nanoscale Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2401.12528 |