节线半金属中\(\mathbb{Z}_2\)单极电荷的量子振荡特征
Quantum Oscillation Signatures of $\mathbb{Z}_2$ Monopole Charge in Nodal-Ring Semimetals
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中文总结 AI 辅助
研究三维节线半金属中节环携带的贝里相位\(w_1\pi\)和\(\mathbb{Z}_2\)单极电荷\(w_2\)，发现磁量子振荡能诊断\(w_2\)，信号与磁场方向有关，还预测弱掺杂的三维ABC堆叠石墨二炔在特定场范围有此振荡。
中文摘要 AI 辅助
拓扑半金属的能带节点具有量化不变量，可出现在体响应中，但一些不变量对标准探针仍隐藏。特别是，能带节点可携带二级拓扑电荷，其输运特征很大程度上未被探索。本文研究三维节线半金属，其中节环携带贝里相位\(w_1\pi\)和\(\mathbb{Z}_2\)单极电荷\(w_2\)。表明通常视为\(w_1\)探针的磁量子振荡可直接诊断\(w_2\)，相关信号由磁场方向选择。对于沿环轴的场，环形费米面的内外极值轨道都环绕\(w_2\)强制的线，并在第\(\nu\)谐波中表现出拓扑相移\(\nu w_2\pi\)，可通过标准相分辨量子振荡分析获取。相比之下，对于垂直于环轴施加的场，相关极值轨道表现出与贝里相位\(w_1\pi\)相关的通常\(\pi\)相移，与\(w_2\)无关。对于弱掺杂，预测三维ABC堆叠石墨二炔在当今高场设施可及的场范围内表现出所提出的振荡。
英文摘要
Topological semimetals host band nodes characterized by quantized invariants that can appear in bulk responses, yet some invariants remain hidden from standard probes. In particular, band nodes can carry secondary topological charges whose transport signatures are still largely unexplored. Here we study three-dimensional nodal-line semimetals in which nodal rings carry both the Berry phase $w_1π$ and a $\mathbb{Z}_2$ monopole charge $w_2$. We show that magnetic quantum oscillations, usually treated as a probe of $w_1$, can directly diagnose $w_2$, with the relevant signal selected by the magnetic-field direction. For a field along the ring axis, the inner and outer extremal orbits of the toroidal Fermi surface both encircle the $w_2$-enforced thread and exhibit a topological phase shift $νw_2π$ in the $ν$th harmonic, which is accessible through standard phase-resolved quantum-oscillation analysis. By contrast, for a field applied perpendicular to the ring axis, the relevant extremal orbit exhibits the usual $π$ phase shift associated with the Berry phase $w_1π$, independent of $w_2$. For weak doping, three-dimensional ABC-stacked graphdiyne is predicted to exhibit the proposed oscillations in a field range accessible with present-day high-field facilities.
