发表机构
Shiv Nadar Institution of Eminence (SNIoE)（Shiv Nadar卓越机构）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究二维狄拉克锥和GNRs在垂直磁场下量子极限时杂质势作用下的直流磁导率，采用久保 - 巴斯汀形式计算输运系数，揭示了两系统不同的输运特征，为GNRs磁输运实验提供理论框架。
AI 中文摘要
我们研究了二维狄拉克锥和带隙节点环（GNRs）在垂直磁场下的直流磁导率，该磁场将电子能谱量子化为朗道能级（LLs）。在超量子极限下，仅最低朗道能级（LLL）部分占据，我们采用久保 - 巴斯汀形式来计算点状、高斯和汤川杂质势的输运系数。对于狄拉克情形，点状杂质的纵向电导率与场无关，高斯和汤川势的纵向电导率是B的单调函数，由于两个相邻LLs的粒子 - 空穴对称性，霍尔电导率恒为零。GNR情形在性质上不同：其非单调的拉伸对勾形LL谱导致有效LLL随着场增加迁移到相继更低的指标，在两种电导率中产生明显的振荡结构。纵向响应在LLL简并处出现共振峰，霍尔电导率在这些相同点处描绘出具有尖锐零交叉的锯齿图案。这些结果在极端量子极限下为两个系统建立了不同的输运特征，并为解释GNRs的磁输运实验提供了理论框架。
英文摘要
We investigate the dc magnetoconductivity of two-dimensional Dirac cones and gapped nodal rings (GNRs) subjected to a perpendicular magnetic field, which quantises the electronic spectrum into Landau levels (LLs). Working in the ultraquantum limit, where only the lowest LL (LLL) is partially occupied, we employ the Kubo--Bastin formalism to compute the transport coefficients for pointlike, Gaussian, and Yukawa impurity-potentials. For the Dirac case, the longitudinal conductivity is field-independent for pointlike impurities and a monotonic function of $B$ for the Gaussian and Yukawa potentials, while the Hall conductivity vanishes identically owing to the particle-hole symmetry of the two neighbouring LLs. The GNR case is qualitatively different: its non-monotonic stretched-checkmark LL spectrum causes the effective LLL to migrate to successively lower indices as the field increases, producing a pronounced oscillatory structure in both conductivities. The longitudinal response develops resonant peaks at LLL degeneracies, while the Hall conductivity traces out a sawtooth pattern with sharp zero-crossings at these same points. These results establish distinct transport fingerprints for the two systems in the extreme quantum limit, and provide a theoretical framework for interpreting magnetotransport experiments on GNRs.
Commentsrevised with realistic parameters for numerical results
