Coherent Spin Precession and Lifetime-Limited Spin Dephasing in CsPbBr3 Perovskite Nanocrystals

TL;DR

This study demonstrates room-temperature coherent spin precession in CsPbBr3 nanocrystals, with spin dephasing times approaching the photoluminescence lifetime, highlighting their potential for quantum technologies.

Contribution

It provides the first evidence of room-temperature coherent spin precession in colloidal CsPbBr3 nanocrystals, with spin dephasing times near the emission lifetime.

Findings

Coherent spin precession persists up to room temperature.

Spin dephasing times approach the nanocrystal photoluminescence lifetime.

Thermally activated phonons influence spin coherence at higher temperatures.

Abstract

Carrier spins in semiconductor nanocrystals are promising candidates for quantum information processing. Using a combination of time-resolved Faraday rotation and photoluminescence spectroscopies, we demonstrate optical spin polarization and coherent spin precession in colloidal CsPbBr3 nanocrystals that persists up to room temperature. By suppressing the influence of inhomogeneous hyperfine fields with a small applied magnetic field, we demonstrate inhomogeneous hole transverse spin-dephasing times (T2*) that approach the nanocrystal photoluminescence lifetime, such that nearly all emitted photons derive from coherent hole spins. Thermally activated LO phonons drive additional spin dephasing at elevated temperatures, but coherent spin precession is still observed at room temperature. These data reveal several major distinctions between spins in nanocrystalline and bulk CsPbBr3 and open the door for using metal-halide perovskite nanocrystals in spin-based quantum technologies.