Chiral crystal structure and split Fermi surface properties in TaSi ₂

We carried out a de Haas-van Alphen (dHvA) experiment in TaSi ₂with the hexagonal chiral structure, together with an energy band calculation. The Fermi surface is found to be split into two different Fermi surfaces, reflecting the non-centrosymmetric crystal structure. The magnitude of the antisymmetric spin-orbit interaction or the splitting energy between the two Fermi surfaces is determined to be 493 K for dHvA branch α (α'), 564 K for branch β (β'), and 617K for branch γ (γ'), where these dHvA branches correspond to the main Fermi surfaces. The present splitting values are compared with 19, 39, and 110K, respectively, observed in a similar compound, VSi₂. The splitting energy is found to be larger in Ta-5d conduction electrons than in V-3d conduction electrons. Furthermore, we found a magnetic breakthrough effect for branches γ (γ') and α (α'), of which the circulating orbits are separate but are nearly degenerate in three and two regions, respectively.