AI 中文总结
本研究针对节点线半金属，利用双带有效哈密顿量和波函数匹配方法，揭示磁势垒可作为通道选择型过滤器，通过依次阻断环形费米面的内外输运通道，为观测其环形费米面提供实验指纹。
AI 中文摘要
我们研究节点线半金属中通过磁势垒的量子输运。当费米能级靠近节点环时，费米面呈环形几何结构，平行于节点环的平面内的每个截面都包含两个同心轮廓，即内轮廓与外轮廓，承载着不同的输运通道。我们证明磁势垒可区分这两个通道：由于两个轮廓包围的动量空间面积不同，它们对场诱导的横向动量偏移的响应不同，且内轮廓比外轮廓在更弱的势垒强度下被截断。利用双带有效哈密顿量和波函数匹配方法，我们得到了闭合形式的通道分辨透射振幅。在有限的势垒强度窗口内，内轮廓被完全阻挡而外轮廓仍可透射，因此该势垒起到通道选择型过滤器的作用。这种依次淬灭的行为决定了两端电导随势垒强度的变化规律，即电导随势垒强度下降，对应两个通道依次关闭，直至外通道被截断，这为节点线半金属的环形费米面提供了可实验观测的特征指纹。
英文摘要
We study quantum transport through a magnetic barrier in a nodal-line semimetal. When the Fermi energy lies near the nodal ring, the Fermi surface has toroidal geometry. Each cross-section in a plane parallel to the nodal ring consists of two concentric contours, inner and outer, carrying distinct transport channels. We show that a magnetic barrier resolves these two channels: because the contours enclose different momentum-space areas, they accommodate the field-induced transverse-momentum shift unequally, and the inner channel is cut off at a weaker barrier strength than the outer. Using a two-band effective Hamiltonian and a wave-function matching approach, we obtain closed-form, channel-resolved transmission amplitudes. Over a finite window of barrier strength the inner contour is fully blocked while the outer still transmits, so the barrier acts as a channel-selective filter. This sequential quenching shapes the two-terminal conductance, which decreases with barrier strength as the two channels close in turn and terminates once the outer channel is cut off, providing experimentally accessible fingerprints of the toroidal Fermi surface of a nodal-line semimetal.
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