Bright magnetic dipole radiation from two-dimensional lead-halide perovskites

TitleBright magnetic dipole radiation from two-dimensional lead-halide perovskites
Publication TypeJournal Article
Year of Publication2020
AuthorsDeCrescent, Ryan A., Naveen R. Venkatesan, Clayton J. Dahlman, Rhys M. Kennard, Xie Zhang, Wenhao Li, Xinhong Du, Michael L. Chabinyc, Rashid Zia, and Jon A. Schuller
JournalScience Advances
Date Published02/2020

Light-matter interactions in semiconductors are uniformly treated within the electric dipole approximation; multipolar interactions are considered “forbidden.” We experimentally demonstrate that this approximation inadequately describes light emission in two-dimensional (2D) hybrid organic-inorganic perovskites (HOIPs), solution processable semiconductors with promising optoelectronic properties. By exploiting the highly oriented crystal structure, we use energy-momentum spectroscopies to demonstrate that an exciton-like sideband in 2D HOIPs exhibits a multipolar radiation pattern with highly directed emission. Electromagnetic and quantum-mechanical analyses indicate that this emission originates from an out-of-plane magnetic dipole transition arising from the 2D character of electronic states. Symmetry arguments and temperature-dependent measurements suggest a dynamic symmetry-breaking mechanism that is active over a broad temperature range. These results challenge the paradigm of electric dipole–dominated light-matter interactions in optoelectronic materials, provide new perspectives on the origins of unexpected sideband emission in HOIPs, and tease the possibility of metamaterial-like scattering phenomena at the quantum-mechanical level.