Ultrafast Control of Excitonic Rashba Fine Structure by Phonon Coherence in the Metal Halide Perovskite ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}$

Ultrafast Control of Excitonic Rashba Fine Structure by Phonon Coherence in the Metal Halide Perovskite ${CH}_{3} {NH}_{3} {PbI}_{3}$

Z. Liu, C. Vaswani, X. Yang, X. Zhao, Y. Yao, Z. Song, D. Cheng, Y. Shi, L. Luo, D.-H. Mudiyanselage, C. Huang, J.-M. Park, R. H. J. Kim, J. Zhao, Y. Yan, K.-M. Ho, and J. Wang

Phys. Rev. Lett. 124, 157401 – Published 16 April 2020

Abstract

We discover hidden Rashba fine structure in ${CH}_{3} {NH}_{3} {PbI}_{3}$ and demonstrate its quantum control by vibrational coherence through symmetry-selective vibronic (electron-phonon) coupling. Above a critical threshold of a single-cycle terahertz pump field, a Raman phonon mode distinctly modulates the middle excitonic states with persistent coherence for more than ten times longer than the ones on two sides that predominately couple to infrared phonons. These vibronic quantum beats, together with first-principles modeling of phonon periodically modulated Rashba parameters, identify a threefold excitonic fine structure splitting, i.e., optically forbidden, degenerate dark states in between two bright ones with a narrow, $\sim 3 nm$ splitting. Harnessing of vibronic quantum coherence and symmetry inspires light-perovskite quantum control and sub-THz-cycle “Rashba engineering” of spin-split bands for ultimate multifunction device.

Received 14 December 2019
Revised 17 February 2020
Accepted 13 March 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.157401

Physics Subject Headings (PhySH)

Excitons Phonons Rashba coupling Ultrafast optics

Semiconductor compounds

Photoexcitation Terahertz spectroscopy Ultrafast pump-probe spectroscopy

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Z. Liu^1,†, C. Vaswani^1,†, X. Yang¹, X. Zhao¹, Y. Yao¹, Z. Song ², D. Cheng¹, Y. Shi ³, L. Luo¹, D.-H. Mudiyanselage¹, C. Huang ¹, J.-M. Park¹, R. H. J. Kim ¹, J. Zhao³, Y. Yan², K.-M. Ho¹, and J. Wang ^1,*

¹Department of Physics and Astronomy and Ames Laboratory-U.S. DOE, Iowa State University, Ames, Iowa 50011, USA
²Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo, Ohio 43606, USA
³ICQD/Hefei National Laboratory for Physical Sciences at the Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China