Optical-Pump Terahertz-Probe Spectroscopy of the Topological Crystalline Insulator Pb 1–x Sn x Se through the Topological Phase Transition
Optical-Pump Terahertz-Probe Spectroscopy of the Topological Crystalline Insulator Pb 1–x Sn x Se through the Topological Phase Transition
复制标题
拓扑晶体绝缘体 Pb 1–x Sn x Se 通过拓扑相变的光泵太赫兹探针光谱
DOI：
10.1021/acsphotonics.1c01717
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发表时间：
2022
期刊：
影响因子：
7
通讯作者：
Burghoff, David
中科院分区：
文献类型：
--
作者：
Xiao, Zhenyang;Wang, Jiashu;Liu, Xinyu;Assaf, Badih A.;Burghoff, David
拓扑晶体绝缘体，其性质由晶体对称性保证的拓扑绝缘体，可以潜在地为太赫兹光电器件提供一个有前途的平台，因为它们的性质可以在异质结构中分层时根据需要进行调整。我们执行了拓扑晶体绝缘体的第一个光泵太赫兹探针光谱，使用它们来研究Pb1-xSnxSe作为温度函数的动力学。在低温下，狄拉克费米子的激发导致太赫兹透射率的增加；从这个负光电导率中，可以提取出6 ps的亚带内弛豫速率。在高温下，只有大质量费米子存在，泵浦引起的自由载流子损耗降低了27 ps带间寿命期间的太赫兹传输。这两种效应都存在于接近拓扑到平凡转变的温度。我们的实验观察结果为Pb1-xSnxSe的潜在应用提供了关键细节，并提供了对Pb1-xSnxSe异质结构拓扑特性的直接测量。
Topological crystalline insulators, topological insulators whose properties are guaranteed by crystalline symmetry, can potentially provide a promising platform for terahertz optoelectronic devices, as their properties can be tuned on demand when layered in heterostructures. We perform the first optical-pump terahertz-probe spectroscopy of topological crystalline insulators, using them to study the dynamics of Pb1–xSnxSe as a function of temperature. At low temperatures, excitation of Dirac fermions leads to an increase in terahertz transmission; from this negative photoconductivity, the intrasubband relaxation rate of 6 ps is extracted. At high temperatures, where only massive Fermions exist, the free-carrier losses induced by the pump reduce the terahertz transmission for the duration of the 27 ps interband lifetime. Both effects are present at temperatures near the topological-to-trivial transition. Our experimental observations provide critical details for potential applications of Pb1–xSnxSe and provide a direct measurement of the topological character of Pb1–xSnxSe heterostructures.