Influence of Geometric Features of Nodal Lines on Transport Properties in Topological Nodal Line Semimetals

Topological nodal line semimetals have attracted significant attention due to their nontrivial topological properties, which arise from the linear crossing of valence and conduction bands forming continuous nodal lines or loops in momentum space. The geometry of these nodal lines has crucial impact on the surface states and transport properties of materials. In this work, we focus on three typical nodal line geometries straight, curved, and loop, and study their effects on the transport property. Based on the variation of three hopping parameters (t1, t2, t3), we obtain a parametric phase diagram that encompasses straight, curved, and loop nodal line semimetal phases as well as semiconductor phases. Our findings reveal that the low-order nearest-neighbor hopping (t1, t2) determine whether the material is a semiconductor or a semimetal, whereas the high-order hopping (t3) influences the specific geometric shape of the nodal line. The dispersion of low-energy states at different nodes along the nodal line indicates that nodes on high-symmetry paths generally have larger Fermi velocities. The trend of the maximum Fermi velocity changes in opposition to the direction of nodal line curvature. Furthermore, the degree of nodal line bending shows a clear negative correlation with the material’s magnetoresistance. These results not only deepen the understanding of the geometric features of nodal distribution in topological nodal line semimetals but also reveal the influence of nodal line geometry on transport properties, providing a theoretical foundation for material design and application.