在Na3Bi中观察到体3D Dirac多重态、Lifshitz跃迁和嵌套自旋态
Observation of a bulk 3D Dirac multiplet, Lifshitz transition, and nestled spin states in Na3Bi
摘要：
二维和三维中的对称性或拓扑保护的狄拉克费米子态构成了展现奇异物理现象的新颖量子系统。然而，没有研究的自旋轨道材料是适合实现体多重态狄拉克探索相互作用的狄拉克物理。在这里，我们提出的实验证据，第一次，该化合物Na 3Bi主机散装自旋轨道狄拉克多重态和它们的相互作用或重叠导致在动量空间的Lifshitz过渡-实现相互作用的条件涉及狄拉克状态。通过在非自然解理（100）晶体表面仔细制备样品，我们利用高分辨率角分辨和自旋分辨光电子能谱测量揭示了Na 3Bi中许多新的电子和自旋性质。我们观察到两个位于体区中心点$Γ$两侧的体三维狄拉克节点，它们表现出费米面Lifshitz转变和鞍点奇异性。此外，我们的数据表明，理论预测的弱二维非平凡自旋轨道表面态的可能存在的证据与螺旋自旋极化，坐落在两个体狄拉克锥之间，与理论计算的（100）表面弧模式一致。我们的主要实验观察的狄拉克结构和Lifshitz转变的丰富的多重态打开了大门，诱导电子不稳定性和相关的物理现象在Na 3Bi，并铺平了道路，工程的新的拓扑状态使用Na 3Bi在最近的理论预测。
英文摘要：
Symmetry or topology protected Dirac fermion states in two and three dimensions constitute novel quantum systems that exhibit exotic physical phenomena. However, none of the studied spin-orbit materials are suitable for realizing bulk multiplet Dirac states for the exploration of interacting Dirac physics. Here we present experimental evidence, for the first time, that the compound Na3Bi hosts a bulk spin-orbit Dirac multiplet and their interaction or overlap leads to a Lifshitz transition in momentum space - a condition for realizing interactions involving Dirac states. By carefully preparing the samples at a non-natural-cleavage (100) crystalline surface, we uncover many novel electronic and spin properties in Na3Bi by utilizing high resolution angle- and spin-resolved photoemission spectroscopy measurements. We observe two bulk 3D Dirac nodes that locate on the opposite sides of the bulk zone center point $Γ$, which exhibit a Fermi surface Lifshitz transition and a saddle point singularity. Furthermore, our data shows evidence for the possible existence of theoretically predicted weak 2D nontrivial spin-orbit surface state with helical spin polarization that are nestled between the two bulk Dirac cones, consistent with the theoretically calculated (100) surface-arc-modes. Our main experimental observation of a rich multiplet of Dirac structure and the Lifshitz transition opens the door for inducing electronic instabilities and correlated physical phenomena in Na3Bi, and paves the way for the engineering of novel topological states using Na3Bi predicted in recent theory.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
