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arXiv · 2408.01982

Two-dimensional Topological Ferroelectric Metal with Giant Shift Current

Liu Yang·Lei Li·Zhi-Ming Yu·Menghao Wu·Yugui Yao
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Abstract

The pursuit for "ferroelectric metal" which combines seemingly incompatible spontaneous electric polarization and metallicity, has been assiduously ongoing but remains elusive. Unlike traditional ferroelectrics with a wide band gap, ferroelectric (FE) metals can naturally incorporate nontrivial band topology near the Fermi level, endowing them with additional exotic properties. Here, we show first-principles evidence that the metallic PtBi2 monolayer is an intrinsic two-dimensional (2D) topological FE metal, characterized by out-of-plane polarization and a moderate switching barrier. Moreover, it exhibits a topologically nontrivial electronic structure with Z2 invariant equal to 1, leading to a significant FE bulk photovoltaic effect. A slight strain can further enhance this effect to a remarkable level, which far surpass that of previously reported 2D/3D FE materials. Our work provides an important step towards realizing intrinsic monolayer topological FE metals and paves a promising way for future nonlinear optical devices.

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Liu Yang, Lei Li, Zhi-Ming Yu, Menghao Wu, Yugui Yao. 2024-08-04. Two-dimensional Topological Ferroelectric Metal with Giant Shift Current. https://doi.org/10.1103/physrevlett.133.186801

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