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arXiv · 2111.03183

Optical-pump terahertz-probe spectroscopy of the topological crystalline insulator Pb1-xSnxSe through the topological phase transition

Zhenyang Xiao·Jiashu Wang·Xinyu Liu·Badih Assaf·David Burghoff
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Abstract

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.

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Zhenyang Xiao, Jiashu Wang, Xinyu Liu, Badih Assaf, David Burghoff. 2021-11-04. Optical-pump terahertz-probe spectroscopy of the topological crystalline insulator Pb1-xSnxSe through the topological phase transition. https://arxiv.org/abs/2111.03183

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