The convergence of crystalline symmetry, spin-orbit coupling (SOC), and electron correlations provides a powerful route to realizing quantum states with nontrivial topology and exotic transport responses. Here, the discovery of a topological semimetallic state is reported in BiRe₂O₆, a newly identified 5d metallic oxide that combines low carrier density with high mobility and nonsymmorphic symmetry protection. Density functional theory (DFT) calculations and angle-resolved photoemission spectroscopy (ARPES) measurements reveal the presence of gapless Dirac cones located at high symmetry points of the Brillouin zone, stabilized by nonsymmorphic symmetry and robust against strong SOC. This results in a remarkably high mobility of 1. 95 × 104 cm² V^−1 s^−1 and large magnetoresistance (MR). Angle-dependent magnetotransport measurements further uncover a field-induced butterfly-like anisotropic magnetoresistance (AMR), reflecting the orbital motion of carriers on an anisotropic Fermi surface. Additionally, de Haas-van Alphen (dHvA) quantum oscillations demonstrate a quasi-2D Fermi surface with nontrivial band topology, consistent with both DFT and ARPES results. While the experimental and DFT band structures align at U = 0, the Kadowaki-Woods and Wilson ratios suggest moderate electronic correlations. These findings establish BiRe₂O₆ as a promising platform for investigating the interplay of topological protection, SOC, and electron correlations in low-density 5d oxides.
Yanda et al. (Wed,) studied this question.