用核磁共振证明ZrTe $_2$中的拓扑节线
Topological nodal line in ZrTe$_2$ demonstrated by nuclear magnetic resonance
摘要：
在这项工作中，我们报告的核磁共振（NMR）结合密度泛函理论（DFT）的研究过渡金属二硫属化物ZrTe $_2$。测得的NMR位移各向异性揭示了准二维行为连接到一个拓扑节点线接近费米能级。在磁场垂直于ZrTe $_2$层的情况下，测量的位移可以很好地拟合由高迁移率狄拉克电子引起的增强的抗磁性和自旋位移的组合。自旋晶格弛豫速率与外场平行和垂直的层在低温下匹配的预期行为与扩展的轨道超精细相互作用由于准2D狄拉克载流子。此外，计算的能带结构也表明在ZrTe $_2$中存在$Γ$和A之间的节线.对于中间温度，自旋-晶格弛豫速率急剧降低，这可以解释为由于这些载流子的寿命降低，这与在相同温度范围内迁移率的大变化相匹配。在200 K以上，局部轨道贡献开始占主导地位的轨道弛豫机制揭示了原子功能的混合物。
英文摘要：
In this work, we report nuclear magnetic resonance (NMR) combined with density functional theory (DFT) studies of the transition metal dichalcogenide ZrTe$_2$. The measured NMR shift anisotropy reveals a quasi-2D behavior connected to a topological nodal line close to the Fermi level. With the magnetic field perpendicular to the ZrTe$_2$ layers, the measured shift can be well-fitted by a combination of enhanced diamagnetism and spin shift due to high mobility Dirac electrons. The spin-lattice relaxation rates with external field both parallel and perpendicular to the layers at low temperatures match the expected behavior associated with extended orbital hyperfine interaction due to quasi-2D Dirac carriers. In addition, calculated band structures also show clear evidence for the existence of nodal line in ZrTe$_2$ between $Γ$ and A. For intermediate temperatures, there is a sharp reduction in spin-lattice relaxation rate which can be explained as due to a reduced lifetime for these carriers, which matches the reported large change in mobility in the same temperature range. Above 200 K, the local orbital contribution starts to dominate in an orbital relaxation mechanism revealing the mixture of atomic functions.
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