Metallic iridium oxides (iridates) provide a fertile playground to explore new phenomena resulting from the interplay between topological protection, spin-orbit and electron-electron interactions. To date, however, few studies of the low energy electronic excitations exist due to the difficulty in synthesising crystals with sufficiently large carrier mean-free-paths. Here, we report the observation of Shubnikov-de Haas quantum oscillations in high-quality single crystals of monoclinic SrIrO₃ in magnetic fields up to 35 T. Analysis of the oscillations reveals a Fermi surface comprising multiple small pockets with effective masses up to 4.5 times larger than the calculated band mass. Ab-initio calculations reveal robust linear band-crossings at the Brillouin zone boundary, due to its non-symmorphic symmetry, and overall we find good agreement between the angular dependence of the oscillations and the theoretical expectations. Further evidence of strong electron correlations is realized through the observation of signatures of non-Fermi liquid transport as well as a large Kadowaki-Woods ratio. These collective findings, coupled with knowledge of the evolution of the electronic state across the Ruddlesden-Popper iridate series, establishes monoclinic SrIrO₃ as a topological semimetal on the boundary of the Mott metal-insulator transition.

金属铱氧化物（铱酸盐）为探索拓扑保护、自旋轨道和电子-电子相互作用之间相互作用产生的新现象提供了一个肥沃的游乐场。然而，迄今为止，由于难以合成具有足够大载流子平均自由程的晶体，因此对低能电子激发的研究很少。在这里，我们报告了在高质量单斜 SrIrO ₃单晶中对 Shubnikov-de Haas 量子振荡的观察在高达 35 T 的磁场中。振荡分析显示费米表面包含多个小口袋，有效质量比计算的带质量大 4.5 倍。Ab-initio 计算揭示了布里渊区边界处的稳健线性带交叉，由于其非对称对称性，总体而言，我们发现振荡的角度依赖性与理论预期之间具有良好的一致性。通过观察非费米液体传输的特征以及大的门胁伍兹比率，实现了强电子相关性的进一步证据。这些集体发现，再加上对 Ruddlesden-Popper iridate 系列电子状态演变的了解，建立了单斜晶 SrIrO ₃ 作为莫特金属-绝缘体过渡边界上的拓扑半金属。