Oral: Crystallographic defects in Weyl semimetal LaAlGe

In LaAlGe, one of the Weyl semimetal family LnAlX (Ln = lanthanide, X = Ge, Si), despite that the Fermi arc electron states on the surface were measured through the angle-resolved photoemission spectroscopy [1], neither anomalous Hall effect nor chiral anomaly was observed [2,3]. The LaAlGe single crystals are typically grown out of Al self-flux because of its low melting point [2,3]. The volatile nature of Al may result in various crystallographic defects during the crystal growth, which can play a role in above the discrepancy. Therefore, it is crucial to understand the defect energetics at the growth level. In this work, we investigated the native crystallographic defects including vacancy and antisite in Weyl semimetal LaAlGe using hybrid density-functional theory calculations [4]. Based on the results, the most abundant defects are figured out, and the role of these defects are discussed.

[1] S.-Y. Xu et al., Sci. Adv. 3, e1603266 (2017).

[2] H. Hodovanets et al., Phys. Rev. B 98, 245132 (2018).

[3] Z. Hu et al., Appl. Phys. Lett. 117, 222410 (2020).

[4] I. Kim et al., Phys. Rev. Mater. 8.5, 054203 (2024).