Abstract
The atomic and electronic dynamics in the topological insulator (TI) Bi2Te3 under strong photoexcitation were characterized with time-resolved electron diffraction and time-resolved mid-infrared spectroscopy. Three-dimensional TIs characterized as bulk insulators with an electronic conduction surface band have shown a variety of exotic responses in terms of electronic transport when observed under conditions of applied pressure, magnetic field, or circularly polarized light. However, the atomic motions and their correlation between electronic systems in TIs under strong photoexcitation have not been explored. The artificial and transient modification of the electronic structures in TIs via photoinduced atomic motions represents a novel mechanism for providing a comparable level of bandgap control. The results of time-domain crystallography indicate that photoexcitation induces two-step atomic motions: first bismuth and then tellurium center-symmetric displacements. These atomic motions in Bi2Te3 trigger 10% bulk bandgap narrowing, which is consistent with the time-resolved mid-infrared spectroscopy results.
Highlights
Show that photoinduced atomic motions can be correlated to change in the electronic bandgap of topological insulator (TI)
We examine the possibility of the artificial modification of the electronic structure in Bi2Te3 by interband photoexcitation via atomic motions occurring along the excited state surface
We discuss the correlation between the atomic motions and the change in the electronic structure of the Bi2Te3 system by comparing the results from the Time-resolved electron diffraction (Tr-ED) and NUV pump and MIR probe reflection spectroscopy
Summary
Show that photoinduced atomic motions can be correlated to change in the electronic bandgap of TIs. We examine the possibility of the artificial modification of the electronic structure in Bi2Te3 by interband photoexcitation via atomic motions occurring along the excited state surface
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