Exciton spin states in nanocrystal quantum dots revealed by spin-polarized resonant photoluminescence and raman spectroscopy

Madalina Furis, Todd Barrick, Patrick Robbins, Scott A. Crooker, Melissa Petruska, Victor Klimov, Al L. Efros

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

We performed spin-polarized resonant Raman and resonant photoluminescence excitation spectroscopy (also known as "fluorescence line narrowing") on ZnS-capped CdSe nanocrystal quantum dots in high magnetic fields to 33 Tesla and temperatures down to 1.7K, which allows detailed investigation of the excitonic spin states. In these experiments, spin-polarized electrons and holes are resonantly injected by circularly polarized light into colloidal quantum dots of specific size, using a narrowband tunable dye laser and a fiber-coupled probe that is specially-designed for use in high-field magnets. In addition to the expected broad features associated with excitonic recombination and Raman-like peaks associated with quantized acoustic phonons, the photoluminescence spectra measured at magnetic fields larger than 10 Tesla develop a sharp peak, which moves roughly linearly with applied magnetic field. Further, the energy of this high-field peak varies systematically as a function of nanocrystal size. However, unlike typical electron spin flip transitions, the mode energy extrapolates to a finite value at zero magnetic field, suggesting the existence of an additional size-dependent exchange mechanism.

Original languageEnglish
Pages (from-to)3769-3774
Number of pages6
JournalInternational Journal of Modern Physics B
Volume18
Issue number27-29
DOIs
Publication statusPublished - Nov 30 2004

Keywords

  • CdSe nanocrystals
  • Line-narrowing
  • Photoluminescence
  • Zeeman splitting

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Condensed Matter Physics

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