Ultrafast carrier-lattice interactions and interlayer modulations of Bi2Se3 by X-ray free electron laser diffraction

Abstract

As a 3D topological insulator, bismuth selenide (Bi2Se3) has potential applications for electrically and optically controllable magnetic and optoelectronic devices. How the carriers interact with lattice is important to understand the coupling with its topological phase. It is essential to measure with a time scale smaller than picoseconds for initial interaction. Here we use an X-ray free-electron laser to perform time-resolved diffraction to study ultrafast carrier-induced lattice contractions and interlayer modulations in Bi2Se3 thin films. The lattice contraction depends on the carrier concentration and is followed by an interlayer expansion accompanied by oscillations. Using density functional theory (DFT) and the Lifshitz model, the initial contraction can be explained by van der Waals force modulation of the confined free carrier layers. Band inversion, related to a topological phase transition, is modulated by the expansion of the interlayer distance. These results provide insight into instantaneous topological phases on ultrafast timescales.

References in corpus (4)

• Bulk Band Gap and Surface State Conduction Observed in Voltage-Tuned Crystals of the Topological Insulator Bi${}_2$Se${}_3$
• Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
• Distinguishing bulk and surface electron-phonon coupling in the topological insulator Bi2Se3 using time-resolved photoemission spectroscopy
• Acoustic phonon dynamics in thin-films of the topological insulator Bi2Se3

Cited by in corpus (6)

• Ultrafast carrier-coupled interlayer contraction, coherent intralayer motions, and phonon thermalization dynamics of black phosphorus
• Multiphoton-pumped UV-Vis transient absorption spectroscopy of 2D materials: basic concepts and recent applications
• Two-photon IR pumped UV-Vis transient absorption spectroscopy of Dirac fermions in the 2D and 3D topological insulator Bi2Se3
• Ultrafast switching of topological invariants by light-driven strain
• Atomically Resolved Acoustic Dynamics Coupled with Magnetic Order in a van der Waals Antiferromagnet
• Tracking the surface atomic motion in a coherent phonon oscillation