Title: Magnetic properties of candidate Weylsemimetals Ln3TiBi5
Abstract: Topological semimetals (TSMs)are a class of gapless quantum materials exhibiting protected band crossing in the bulk band structure and vanished density of states near the Fermi energy. The most common TSMs are Dirac semimetals (DSMs) and Weyl semimetals (WSMs)with corresponding Dirac and Weyl points, where the Dirac point is 4-fold degenerate, while the Weyl point is 2-fold degenerate. The breaking of either inversion symmetry or time-reversal symmetry in DSMs results in
WSMs. In 2020, Klemenz et al. proposed simple chemical rules as a powerful tool for predicting TSMs [1]. They proposed two requirements to be a TSM: 1) two chemically equivalent atoms per unit cell; 2) extended hypervalent bonds. The former enables band folding, which brings about band inversion and thereby causes band crossing, a primary source for a topological phase. Extended hypervalent bonds are electron-rich, multicenter chemical bonding where electrons delocalize over a structural motif. These hypervalent bonds can both stabilize the topological band structure and make the material more robust to defects that would otherwise cause dispersed bands. In this work, I will discuss materials Ln3TiBi5 (Ln = Pr, Nd, Gd) that fit these two requirements and thus are good candidates for WSMs. We performed single crystal growth, as well as studies to investigate the magnetic and heat capacity properties of these compounds.
[1] Klemenz, S. et al. (2020)“The Role of Delocalized Chemical Bonding in Square-Net-Based Topological Semimetals,” Journal of the American Chemical Society, 142(13), pp.6350–6359. Available at: https://doi.org/10.1021/jacs.0c01227.