Rapidly expanding spin-polarized exciton halo in a two-dimensional halide perovskite at room temperature

• Published in: Science advances Vol. 8; no. 30; p. eabp8135
• Main Authors: Yumoto, Go, Sekiguchi, Fumiya, Hashimoto, Ruito, Nakamura, Tomoya, Wakamiya, Atsushi, Kanemitsu, Yoshihiko
• Format: Journal Article
• Language: English
• Published: American Association for the Advancement of Science 29.07.2022
• Subjects: Condensed Matter Physics; Materials Science; Physical and Materials Sciences; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.abp8135

Monitoring of the spatially resolved exciton spin dynamics in two-dimensional semiconductors has revealed the formation of a spatial pattern and long-range transport of the spin-polarized excitons, which holds promise for exciton-based spin-optoelectronic applications. However, the spatial evolution has been restricted to cryogenic temperatures because of the short exciton spin relaxation times at room temperature. Here, we report that two-dimensional halide perovskites can overcome this limitation owing to their relatively long exciton spin relaxation times and substantial exciton-exciton interactions. We demonstrate the emergence of a halo-like spatial profile in spin-polarized exciton population and its ultrafast expansion at room temperature by performing time-resolved Faraday rotation imaging of spin-polarized excitons in two-dimensional perovskite (C 4 H 9 NH 3 ) 2 (CH 3 NH 3 ) 3 Pb 4 I 13 . Exciton-exciton exchange interactions induce density-dependent nonlinear relaxation and ultrafast transport of exciton spins and give rise to a rapidly expanding halo-like spatial pattern. The density-dependent spatial control suggests the potential of using two-dimensional halide perovskites for spin-optoelectronic applications. 2D halide perovskites realize room temperature spatial evolution of exciton spins induced by exciton-exciton interactions.