Crystal growth and quantum oscillations in the topological chiral semimetal CoSi

Author(s): Xu, X; Wang, X; Cochran, TA; Sanchez, DS; Chang, G; Belopolski, I; Wang, G; Liu, Y; Tien, HJ; Gui, X; Xie, W; Hasan, MZ; Chang, TR; Jia, S | Abstract: © 2019 American Physical Society. We survey the electrical transport properties of single-crystalline, topological chiral semimetal CoSi grown via different methods. High-quality CoSi single crystals were found in the growth from a tellurium solution. The sample's high carrier mobility enables us to observe quantum oscillations (QOs) in its thermoelectrical signals. Our analysis of QOs reveals two spherical Fermi surfaces around the R point in its Brillouin zone corner. The extracted Berry phases of these electron orbits are consistent with the -2 chiral charge as reported in density functional theory (DFT) calculations. A detailed analysis of the QOs reveals that the spin-orbit-coupling-induced band splitting is less than 2 meV near the Fermi level, one order of magnitude smaller than our DFT calculation. We also report a large phonon-drag-induced Nernst effect in CoSi at intermediate temperatures.