Magnetotransport properties of the layered CaAl2Si2 semimetal hosting multiple nontrivial topological states
Abstract
Combination of different nontrivial topological states in a single material is capable of realizing multiple functionalities and exotic physics, but such materials are still very sparse. We report herein the results of magnetotransport measurements and ab initio calculations on single crystalline CaAl2Si2 semimetal. The transport properties could be well understood in connection with the twoband model, agreeing well with the theoretical calculations indicating four main sheets of Fermi surface consisting of three hole pockets centered at the {\Gamma} point and one electron pocket centered at the M point in the Brillouin zone. The single fundamental frequency imposed in the quantum oscillations of magnetoresistance corresponds to the electron Fermi pocket. Without spinorbit coupling (SOC), the ab initio calculations suggest CaAl2Si2 as a system hosting a topological nodalline setting around the {\Gamma} point in the Brillouin zone close to the Fermi level. Once including the SOC, the fragile nodalline will be gapped and a pair of Dirac points emerge along the high symmetric {\Gamma}A direction, which is about 1.22 eV below the Fermi level. The SOC can also induce a topological insulator state along the {\Gamma}A direction with a gap of about 3 meV. The results demonstrate CaAl2Si2 as an excellent platform for the study of novel topological physics with multiple topological states.
 Publication:

arXiv eprints
 Pub Date:
 November 2019
 arXiv:
 arXiv:1911.03844
 Bibcode:
 2019arXiv191103844S
 Keywords:

 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 17 pages,6 figures