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 3 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 3 and open the door for using metal-halide perovskite nanocrystals in spin-based quantum technologies.
The purpose of the research is to provide HR managers with some guidance, as they develop employee volunteer programs to meet specific workforce needs. Structured interviews were conducted with eight employees. The data suggest that employees who volunteer time believe that such experiences benefit them personally and improve their ability to perform their work duties. There were slight differences in program type, with those employees involved in programs characterized by high management support and commitment tending to perceive that they reap high overall rewards for their volunteer activities. The perceived impact of volunteer activities on employees included: an improved ability to cope with job challenges; the development of contacts and skills that can be used on the job; improved self‐esteem and a sense of pride. These factors can increase employees’ ability to be proactive problem solvers on the job.
Inorganic–organic interfaces: a tutorial on using organic functional groups to enhance the performances and/or enable new functionality of inorganic nanomaterials.
CsPb(Cl 1−x Br x ) 3 (0 ≤ x ≤ 1) nanocrystals and thin films doped with a series of trivalent rare-earth ions (RE 3+ = Y 3+ , La 3+ , Ce 3+ , Gd 3+ , Er 3+ , Lu 3+ ) have been prepared and studied using variable-temperature and time-resolved photoluminescence spectroscopies. We demonstrate that aliovalent (trivalent) doping of this type universally generates a new and oftenemissive defect state ca. 50 meV inside the perovskite band gap, independent of the specific RE 3+ dopant identity or of the perovskite form (nanocrystals vs thin films). Chloride-to-bromide anion exchange is used to demonstrate that this near-band-edge photoluminescence shifts with changing band-gap energy to remain just below the excitonic luminescence for all compositions of CsPb(Cl 1−x Br x ) 3 (0 ≤ x ≤ 1). Computations show that this shift stems from the effect of the changing lattice dielectric constants on a shallow defect-bound exciton. Microscopic descriptions of this dopant-induced near-band-edge state and its relation to quantum cutting in Yb 3+ -doped CsPb(Cl 1−x Br x ) 3 are discussed.
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