Crane Matthew J, Jacoby Laura M, Cohen Theodore A, Huang Yunping, Luscombe Christine K, Gamelin Daniel R
Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States.
Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195-1652, United States.
Nano Lett. 2020 Dec 9;20(12):8626-8633. doi: 10.1021/acs.nanolett.0c03329. Epub 2020 Nov 25.
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 CsPbBr 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 () 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 CsPbBr and open the door for using metal-halide perovskite nanocrystals in spin-based quantum technologies.
半导体纳米晶体中的载流子自旋是量子信息处理的理想候选者。通过结合时间分辨法拉第旋转和光致发光光谱，我们证明了胶体 CsPbBr 纳米晶体中的光学自旋极化和相干自旋进动，这种现象在室温下依然存在。通过施加小磁场抑制非均匀超精细场的影响，我们证明了非均匀空穴横向自旋退相干时间（）接近纳米晶体的光致发光寿命，使得几乎所有发射的光子都来自相干空穴自旋。热激活的纵光学声子在高温下驱动额外的自旋退相干，但在室温下仍可观察到相干自旋进动。这些数据揭示了纳米晶 CsPbBr 和块状 CsPbBr 中自旋的几个主要区别，并为在基于自旋的量子技术中使用金属卤化物钙钛矿纳米晶体打开了大门。
