Band Engineering of Dirac Semimetals Using Charge Density Waves

We now know that topological materials are anything but rare – between 30 and 50 % of materials have been predicted to be topological [1]. However, a very common issue of and compound with an “interesting” band structure is that most of the time, the feature of interest is convoluted with trivial bands. In this talk, I will show that we can take advantage of a charge density wave (CDW) to gap out such interfering bands, while keeping a nonsymmorphic Dirac node intact. This way we could design the first nonsymmorphic Dirac semimetal in which the Dirac node lies at the Fermi level, while the interference of other bands is minimal [2].  The concept can be expanded to a family of materials in the LnSbxTe2-x system. I will also discuss the physical properties of these materials, which range from unusual transport phenomena to complex magnetism, involving the possibility of skyrmions as well as a “devil’s staircase” [3-4]. 

 

[1] Vergniory, Maia G., et al. "All Topological Bands of All Stoichiometric Materials." arXiv preprint arXiv:2105.09954(2021).

[2] Lei, Shiming, et al. "Band Engineering of Dirac Semimetals Using Charge Density Waves." Advanced Materials (2021): 2101591.

[3] Lei, Shiming, Audrey Saltzman, and Leslie M. Schoop. "Complex magnetic phases enriched by charge density waves in the topological semimetals GdSb x Te 2− x− δ." Physical Review B 103.13 (2021): 134418.

[4] Singha, Ratnadwip, et al. "Evolving Devil's staircase magnetization from tunable charge density waves in nonsymmorphic Dirac semimetals." Advanced Materials 33.41 (2021): 2103476.