Sizable superconducting gap and anisotropic chiral topological superconductivity in the Weyl semimetal PtBi$_2$
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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866909694851809280 |
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| author | Huang, Xiaochun Zhao, Lingxiao Schimmel, Sebastian Besproswanny, Julia Härtl, Patrick Hess, Christian Büchner, Bernd Bode, Matthias |
| author_facet | Huang, Xiaochun Zhao, Lingxiao Schimmel, Sebastian Besproswanny, Julia Härtl, Patrick Hess, Christian Büchner, Bernd Bode, Matthias |
| contents | Topological superconductors offer a fertile ground for realizing Majorana zero modes -- topologically protected, zero-energy quasiparticles that are resilient to local perturbations and hold great promise for fault-tolerant quantum computing. Recent studies have presented encouraging evidence for intrinsic topological superconductivity in the Weyl semimetal trigonal PtBi$_2$, hinting at a robust surface phase potentially stable beyond the McMillan limit. However, due to substantial spatial variations in the observed superconducting (SC) gap $Δ$ the nature of the underlying order parameter $Δ$($k$) remained under debate. Here we report the realization of sizable surface SC gaps ($Δ> 10\,\mathrm{meV}$) in PtBi$_2$, exhibiting remarkable spatial uniformity from hundreds of nanometers down to the atomic level, as revealed by scanning tunneling microscopy and spectroscopy. Building on this spatial homogeneity -- indicative of long-range phase coherence -- we uncover previously unobserved low-energy Andreev bound states (ABSs) that ubiquitously emerge within the SC gap across the surface. Theoretical simulations that closely reproduce the experimental spectra, reveal an anisotropic chiral pairing symmetry of $Δ$($k$), and further suggest that the observed ABSs are of topological origin. The combination of a large, nontrivial pairing gap and accessible surface states establishes PtBi$_2$ as a compelling platform for investigating topological superconductivity and its associated Majorana modes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_13843 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Sizable superconducting gap and anisotropic chiral topological superconductivity in the Weyl semimetal PtBi$_2$ Huang, Xiaochun Zhao, Lingxiao Schimmel, Sebastian Besproswanny, Julia Härtl, Patrick Hess, Christian Büchner, Bernd Bode, Matthias Superconductivity Materials Science Topological superconductors offer a fertile ground for realizing Majorana zero modes -- topologically protected, zero-energy quasiparticles that are resilient to local perturbations and hold great promise for fault-tolerant quantum computing. Recent studies have presented encouraging evidence for intrinsic topological superconductivity in the Weyl semimetal trigonal PtBi$_2$, hinting at a robust surface phase potentially stable beyond the McMillan limit. However, due to substantial spatial variations in the observed superconducting (SC) gap $Δ$ the nature of the underlying order parameter $Δ$($k$) remained under debate. Here we report the realization of sizable surface SC gaps ($Δ> 10\,\mathrm{meV}$) in PtBi$_2$, exhibiting remarkable spatial uniformity from hundreds of nanometers down to the atomic level, as revealed by scanning tunneling microscopy and spectroscopy. Building on this spatial homogeneity -- indicative of long-range phase coherence -- we uncover previously unobserved low-energy Andreev bound states (ABSs) that ubiquitously emerge within the SC gap across the surface. Theoretical simulations that closely reproduce the experimental spectra, reveal an anisotropic chiral pairing symmetry of $Δ$($k$), and further suggest that the observed ABSs are of topological origin. The combination of a large, nontrivial pairing gap and accessible surface states establishes PtBi$_2$ as a compelling platform for investigating topological superconductivity and its associated Majorana modes. |
| title | Sizable superconducting gap and anisotropic chiral topological superconductivity in the Weyl semimetal PtBi$_2$ |
| topic | Superconductivity Materials Science |
| url | https://arxiv.org/abs/2507.13843 |