Stabilization of a non-superconducting, orthorhombic phase by over-hydrogenating LaFeSiH
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arXiv
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| Autores principales: | , , , , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2026
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| _version_ | 1866917429649604608 |
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| author | Hansen, M. F. Lepoittevin, C. Vaney, J. -B. Boullay, P. Nassif, V. Sulpice, A. Mayaffre, H. Julien, M. -H. Tencé, S. Toulemonde, P. |
| author_facet | Hansen, M. F. Lepoittevin, C. Vaney, J. -B. Boullay, P. Nassif, V. Sulpice, A. Mayaffre, H. Julien, M. -H. Tencé, S. Toulemonde, P. |
| contents | Chemical composition provides a powerful route to tune the electronic ground state of iron-based superconductors and other quantum materials, yet access to highly doped phases remains limited. Here we demonstrate that high-pressure thermal decomposition of hydrogen-rich precursors enables over-hydrogenation of LaFeSi. Using anthracene, we synthesize tetragonal superconducting LaFeSiH, including a single hydrogen site, while ammonia borane yields a structurally distorted over-hydrogenated phase, LaFeSiH1+x, with an orthorhombic structure. Chemical analysis reveal excess hydrogen (x ~ 0.6), implying a second H site in LaFeSiH1.6 whose localization and occupancy are determined by neutron diffraction. In contrast to metallic LaFeSi and superconducting LaFeSiH, orthorhombic LaFeSiH1.6 exhibits semiconductor-like behavior. Upon hydrogen release near 100 °C, it transforms into tetragonal superconducting LaFeSiH1+δ (δ << 0.6). These results establish the chemical flexibility of the layered LaFeSiX (X = H, O, F) family and provide access to a high hydrogen-doping regime, creating new opportunities to investigate superconductivity in Fe-based silicides. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_20716 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Stabilization of a non-superconducting, orthorhombic phase by over-hydrogenating LaFeSiH Hansen, M. F. Lepoittevin, C. Vaney, J. -B. Boullay, P. Nassif, V. Sulpice, A. Mayaffre, H. Julien, M. -H. Tencé, S. Toulemonde, P. Superconductivity Chemical composition provides a powerful route to tune the electronic ground state of iron-based superconductors and other quantum materials, yet access to highly doped phases remains limited. Here we demonstrate that high-pressure thermal decomposition of hydrogen-rich precursors enables over-hydrogenation of LaFeSi. Using anthracene, we synthesize tetragonal superconducting LaFeSiH, including a single hydrogen site, while ammonia borane yields a structurally distorted over-hydrogenated phase, LaFeSiH1+x, with an orthorhombic structure. Chemical analysis reveal excess hydrogen (x ~ 0.6), implying a second H site in LaFeSiH1.6 whose localization and occupancy are determined by neutron diffraction. In contrast to metallic LaFeSi and superconducting LaFeSiH, orthorhombic LaFeSiH1.6 exhibits semiconductor-like behavior. Upon hydrogen release near 100 °C, it transforms into tetragonal superconducting LaFeSiH1+δ (δ << 0.6). These results establish the chemical flexibility of the layered LaFeSiX (X = H, O, F) family and provide access to a high hydrogen-doping regime, creating new opportunities to investigate superconductivity in Fe-based silicides. |
| title | Stabilization of a non-superconducting, orthorhombic phase by over-hydrogenating LaFeSiH |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2604.20716 |