Author(s): Xu, KX (Xu, Kai-Xuan); Lai, JM (Lai, Jia-Min); Gao, YF (Gao, Yuan-Fei); Song, FL (Song, Feilong); Sun, YJ (Sun, Yu-Jia); Tan, PH (Tan, Ping-Heng); Zhang, J (Zhang, Jun)

Source: PHYSICAL REVIEW B Volume: 106 Issue: 8 Article Number: 085205 DOI: 10.1103/PhysRevB.106.085205 Published: AUG 15 2022

Abstract: High-order Raman scattering is a typical photophysical process in understanding the electron-phonon coupling (EPC) in materials. In a "soft" polar lattice, due to the strong EPC, the excited electron-hole pairs can be captured by the lattice deformation potential, forming the self-trapped exciton (STE). Although high-order Raman scattering mediated by STE has been predicted by theory, there are rare experimental reports, especially in the double perovskite Cs2Ag0.4Na0.6InCl6, with highly efficient white light emission. We observed high-order Raman mode up to 12 orders at 4 K in Cs2Ag0.4Na0.6InCl6 by resonance excitation. We propose a physical picture of high-order Raman scattering mediated by STE to explain well the linear dependence of frequency and linewidth with order number. A reduction in the EPC with a temperature increase is attributed to the breakdown of momentum conservation during high-order scattering and the delocalization of the STE. Our work deepens the understanding of the EPC in STE and inspires the research of the excited-state decay process.

Accession Number: WOS:000861339500008

ISSN: 2469-9950

eISSN: 2469-9969

Full Text: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.085205