Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
Phys Rev Lett. 2018 Oct 26;121(17):176401. doi: 10.1103/PhysRevLett.121.176401.
We study how nonsymmorphic symmetries that commute with lattice translations are reflected in the quasiparticle interference (QPI) maps measured by scanning tunneling microscopy (STM). QPI maps, which result from scattering of Bloch states off impurities, record the interference of incoming and scattered waves as a function of energy and tip's position. Although both the impurity and the tip generically break spatial symmetries, we find that the QPI maps provide universal information on these symmetries. The symmetries impose constraints on the relation between various momentum components of the Bloch functions. These relations result in selection rules on certain momentum transfers in QPI maps. We find that universal information is encoded in the absence of QPI signal, or in the relative intensity of its replications. We show examples for one-dimensional chains and an effective model of the layered compound ZrSiS. We discuss the implications of our theory in the analysis of observed QPI of the Weyl semimetal TaAs. Our theory is particularly relevant for materials in rod and layer space groups, or when a correlated order parameter, such as antiferromagnetism, enlarges the unit cell.
我们研究了与晶格平移 commute 的非对称对称如何反映在扫描隧道显微镜（STM）测量的准粒子干涉（QPI）图谱中。QPI 图谱是由布洛赫态散射杂质产生的，记录了入射波和散射波的干涉作为能量和探头位置的函数。尽管杂质和探头通常会破坏空间对称性，但我们发现 QPI 图谱提供了关于这些对称性的通用信息。对称性对布洛赫函数的各种动量分量之间的关系施加了约束。这些关系导致 QPI 图谱中某些动量转移的选择规则。我们发现，通用信息编码在 QPI 信号的不存在或其复制的相对强度中。我们展示了一维链和层状化合物 ZrSiS 的有效模型的示例。我们讨论了我们的理论在分析观察到的 Weyl 半金属 TaAs 的 QPI 中的意义。我们的理论对于棒和层空间群中的材料或当相关的序参量（如反铁磁有序）扩大单位胞时特别相关。
