Nonsymmorphic symmetry-protected band crossings in a square-net metal PtPb4

• Published in: npj quantum materials 2022-03, Vol.7 (1), p.1-7, Article 31
• Main Authors: Wu, Han, Hallas, Alannah M., Cai, Xiaochan, Huang, Jianwei, Oh, Ji Seop, Loganathan, Vaideesh, Weiland, Ashley, McCandless, Gregory T., Chan, Julia Y., Mo, Sung-Kwan, Lu, Donghui, Hashimoto, Makoto, Denlinger, Jonathan, Birgeneau, Robert J., Nevidomskyy, Andriy H., Li, Gang, Morosan, Emilia, Yi, Ming
• Format: Article
• Language: English
• Subjects: 639/766/119/2792/4128; 639/766/119/995; ATOMIC AND MOLECULAR PHYSICS; Brillouin zones; Condensed Matter Physics; Crystal structure; Density functional theory; MATERIALS SCIENCE; Metalloids; Physics; Physics and Astronomy; Quantum Physics; Spin-orbit interactions; Structural Materials; Surfaces and Interfaces; Symmetry; Thin Films; Topology
• ISSN: 2397-4648; 2397-4648
• DOI: 10.1038/s41535-022-00441-x

Topological semimetals with symmetry-protected band crossings have emerged as a rich landscape to explore intriguing electronic phenomena. Nonsymmorphic symmetries in particular have been shown to play an important role in protecting the crossings along a line (rather than a point) in momentum space. Here we report experimental and theoretical evidence for Dirac nodal line crossings along the Brillouin zone boundaries in PtPb 4 , arising from the nonsymmorphic symmetry of its crystal structure. Interestingly, while the nodal lines would remain gapless in the absence of spin–orbit coupling (SOC), the SOC, in this case, plays a detrimental role to topology by lifting the band degeneracy everywhere except at a set of isolated points. Nevertheless, the nodal line is observed to have a bandwidth much smaller than that found in density functional theory (DFT). Our findings reveal PtPb 4 to be a material system with narrow crossings approximately protected by nonsymmorphic crystalline symmetries.