具有畸变Sb方网的层状Dirac半金属候选线SrZnSb $_2$中的非平凡拓扑
Non-trivial topology in a layered Dirac nodal-line semimetal candidate SrZnSb$_2$ with distorted Sb square nets
摘要：
层状反铁磁AMnX $_2$（A = Ca/Sr/Ba/Eu/Yb，X=Sb/Bi）材料族中存在Sb/Bi方网为主体的狄拉克态，空间群为P4/nmm或I4/mmm。在本文中，我们提出了一个全面的研究的量子输运行为，角分辨光电子能谱（ARPES）和第一性原理计算的SrZnSb 2，AMnX 2，它的结晶在pnma空间群与扭曲的正方形网络的一个类似物。从35 T的量子振荡测量中，确定了三个主要频率：$_1$ = 103 T，$_2$ = 127 T和$_3$ = 160 T.提取与这些频率相关的准粒子的有效质量，即m* $_1$ = 0.1 m $_e$，m* $_2$ = 0.1 m $_e$和m* $_3$ = 0.09 m $_e$，其中m $_e$是自由电子质量。由三带Lifshitz-Kosevich拟合，F-$_1$、F-$_2$和F-$_3$沿准粒子回旋轨道累积的Berry相位分别为0.06 $π$、1.2 $π$和0.74 $π$.结合ARPES数据和第一性原理计算，我们发现F2和F3与布里渊区边缘的两个非平凡费米口袋有关，而F1与布里渊区中心的平凡费米口袋有关.此外，第一性原理计算进一步证实了SrZnSb $_2$能带结构中Dirac节线的存在.
英文摘要：
Dirac states hosted by Sb/Bi square nets are known to exist in the layered antiferromagnetic AMnX$_2$ (A = Ca/Sr/Ba/Eu/Yb, X=Sb/Bi) material family the space group to be P4/nmm or I4/mmm. In this paper, we present a comprehensive study of quantum transport behaviors, angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations on SrZnSb2, a nonmagnetic analogue to AMnX2, which crystallizes in the pnma space group with distorted square nets. From the quantum oscillation measurements up to 35 T, three major frequencies including F$_1$ = 103 T, F$_2$ = 127 T and F$_3$ = 160 T, are identified. The effective masses of the quasiparticles associated with these frequencies are extracted, namely, m*$_1$ = 0.1 m$_e$, m*$_2$ = 0.1 m$_e$ and m*$_3$ = 0.09m$_e$, where m$_e$ is the free electron mass. From the three-band Lifshitz-Kosevich fit, the Berry phases accumulated along the cyclotron orbit of the quasiparticles are 0.06$π$, 1.2$π$ and 0.74$π$ for F$_1$, F$_2$ and F$_3$, respectively. Combined with the ARPES data and the first-principles calculations, we reveal that F2 and F3 are associated with the two nontrivial Fermi pockets at the Brillouin zone edge while F1 is associated with the trivial Fermi pocket at the zone center. In addition, the first-principles calculations further suggest the existence of Dirac nodal line in the band structure of SrZnSb$_2$.
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