Displacement-Field-Driven Transition between Superconductivity and Valley Ferromagnetism in Transition Metal Dichalcogenides
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866912558028423168 |
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| author | Yang, Hyeok-Jun Hsu, Yi-Ting |
| author_facet | Yang, Hyeok-Jun Hsu, Yi-Ting |
| contents | Recent experiments have observed transitions between superconductivity and correlated magnetism in twisted bilayer WSe$_2$ near van-Hove fillings, driven by the displacement field $D$. Motivated by the experiment, we theoretically propose a general mechanism for a $D$-controlled transition between superconductivity and ferromagnetism in two-dimensional (2D) spin-orbit-coupled hexagonal systems, where van Hove singularities (VHS) lie on the Fermi level. We show that such a transition can be naturally captured by a simple VHS-only model without Fermi surface details, where the inter-VHS interactions that govern the Fermi surface instabilities is controlled by $D$ through the band projection of screened Coulomb interaction. By treating this simple model with renormalization group technique beyond mean-field level, we find that a chiral $d/p$-wave superconductivity naturally dominates under a weak displacement field $D<D_c$. At a stronger displacement field $D>D_c$, a \textit{valley ferromagnetic phase} (vFM) takes over, which is spatially non-uniform due to valley-modulated magnetization. Finally, we discuss generic conditions for the predicted superconductivity-to-ferromagnetism transition to take place in the rich family of few-layer hexagonal van der Waals material systems. Taking twisted bilayer WSe$_2$ as a case study, we discuss experimental detections that can falsify our prediction. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2508_21119 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Displacement-Field-Driven Transition between Superconductivity and Valley Ferromagnetism in Transition Metal Dichalcogenides Yang, Hyeok-Jun Hsu, Yi-Ting Strongly Correlated Electrons Superconductivity Recent experiments have observed transitions between superconductivity and correlated magnetism in twisted bilayer WSe$_2$ near van-Hove fillings, driven by the displacement field $D$. Motivated by the experiment, we theoretically propose a general mechanism for a $D$-controlled transition between superconductivity and ferromagnetism in two-dimensional (2D) spin-orbit-coupled hexagonal systems, where van Hove singularities (VHS) lie on the Fermi level. We show that such a transition can be naturally captured by a simple VHS-only model without Fermi surface details, where the inter-VHS interactions that govern the Fermi surface instabilities is controlled by $D$ through the band projection of screened Coulomb interaction. By treating this simple model with renormalization group technique beyond mean-field level, we find that a chiral $d/p$-wave superconductivity naturally dominates under a weak displacement field $D<D_c$. At a stronger displacement field $D>D_c$, a \textit{valley ferromagnetic phase} (vFM) takes over, which is spatially non-uniform due to valley-modulated magnetization. Finally, we discuss generic conditions for the predicted superconductivity-to-ferromagnetism transition to take place in the rich family of few-layer hexagonal van der Waals material systems. Taking twisted bilayer WSe$_2$ as a case study, we discuss experimental detections that can falsify our prediction. |
| title | Displacement-Field-Driven Transition between Superconductivity and Valley Ferromagnetism in Transition Metal Dichalcogenides |
| topic | Strongly Correlated Electrons Superconductivity |
| url | https://arxiv.org/abs/2508.21119 |