%0 Journal Article %1 Muechler_2019 %A Muechler, Lukas %A Guguchia, Zurab %A Orain, Jean-Christophe %A Nuss, Jürgen %A Schoop, Leslie M. %A Thomale, Ronny %A von Rohr, Fabian O. %D 2019 %I AIP Publishing %J APL Mater. %K a %N 12 %P 121103 %R 10.1063/1.5124242 %T Superconducting order parameter of the nodal-line semimetal NaAlSi %U https://doi.org/10.1063%2F1.5124242 %V 7 %X Nodal-line semimetals are topologically nontrivial states of matter featuring band crossings along a closed curve, i.e., nodal-line, in momen-tum space. Through a detailed analysis of the electronic structure, we show, for the first time, that the normal state of the superconductor NaAlSi, with a critical temperature of Tc ≈ 7 K, is a nodal-line semimetal, where the complex nodal-line structure is protected by nonsym-morphic mirror crystal symmetries. We further report on muon spin rotation experiments revealing that the superconductivity in NaAlSi is truly of bulk nature, featuring a fully gapped Fermi-surface. The temperature-dependent magnetic penetration depth can be well described by a two-gap model consisting of two s-wave symmetric gaps with Δ1 = 0.6(2) meV and Δ2 = 1.39(1) meV. The zero-field muon experiment indi-cates that time-reversal symmetry is preserved in the superconducting state. Our observations suggest that, notwithstanding its topologically nontrivial band structure, NaAlSi may be suitably interpreted as a conventional London superconductor, while more exotic superconducting gap symmetries cannot be excluded. The intertwining of topological electronic states and superconductivity renders NaAlSi a prototypical platform to search for unprecedented topological quantum phases.

@article{Muechler_2019, abstract = {Nodal-line semimetals are topologically nontrivial states of matter featuring band crossings along a closed curve, i.e., nodal-line, in momen-tum space. Through a detailed analysis of the electronic structure, we show, for the first time, that the normal state of the superconductor NaAlSi, with a critical temperature of Tc ≈ 7 K, is a nodal-line semimetal, where the complex nodal-line structure is protected by nonsym-morphic mirror crystal symmetries. We further report on muon spin rotation experiments revealing that the superconductivity in NaAlSi is truly of bulk nature, featuring a fully gapped Fermi-surface. The temperature-dependent magnetic penetration depth can be well described by a two-gap model consisting of two s-wave symmetric gaps with Δ1 = 0.6(2) meV and Δ2 = 1.39(1) meV. The zero-field muon experiment indi-cates that time-reversal symmetry is preserved in the superconducting state. Our observations suggest that, notwithstanding its topologically nontrivial band structure, NaAlSi may be suitably interpreted as a conventional London superconductor, while more exotic superconducting gap symmetries cannot be excluded. The intertwining of topological electronic states and superconductivity renders NaAlSi a prototypical platform to search for unprecedented topological quantum phases.}, added-at = {2023-04-25T14:44:11.000+0200}, author = {Muechler, Lukas and Guguchia, Zurab and Orain, Jean-Christophe and Nuss, Jürgen and Schoop, Leslie M. and Thomale, Ronny and von Rohr, Fabian O.}, biburl = {https://www.bibsonomy.org/bibtex/2b52da7e9ee3ce4f6bab625e11112c420/ctqmat}, day = 10, description = {Superconducting order parameter of the nodal-line semimetal NaAlSi}, doi = {10.1063/1.5124242}, interhash = {8651f842ad55303c5f1f56ef02306779}, intrahash = {b52da7e9ee3ce4f6bab625e11112c420}, journal = {APL Mater.}, keywords = {a}, month = {12}, number = 12, pages = 121103, publisher = {AIP Publishing}, timestamp = {2023-10-16T11:35:09.000+0200}, title = {Superconducting order parameter of the nodal-line semimetal NaAlSi}, url = {https://doi.org/10.1063%2F1.5124242}, volume = 7, year = 2019 }