Absorption and Magnetic Circular Dichroism Analyses of Giant Zeeman Splittings in Diffusion-Doped Colloidal Cd1-xMnxSe Quantum Dots

作者：Barrows Charles J; Vlaskin Vladimir A; Gamelin Daniel R^*

来源：Journal of Physical Chemistry Letters, 2015, 6(15): 3076-3081.

DOI：10.1021/acs.jpclett.5b01137

Impurity ions can transform the electronic, magnetic, or optical properties of colloidal quantum dots. Magnetic impurities introduce strong dopant-carrier exchange coupling that generates giant Zeeman splittings (Delta E-Z) of excitonic excited states. To date, Delta E-Z in colloidal doped quantum dots has primarily been quantified by analysis of magnetic circular dichroism (MCD) intensities and absorption line widths (sigma). Here, we report Delta E-Z values detected directly by absorption spectroscopy for the first time in such materials, using colloidal Cd1-xMnxSe quantum dots prepared by diffusion doping. A convenient method for decomposing MCD and absorption data into circularly polarized absorption spectra is presented. These data confirm the widely applied MCD analysis in the low-field, high-temperature regime, but also reveal a breakdown at low temperatures and high fields when Delta E-Z/sigma approaches unity, a situation not previously encountered in doped quantum dots. This breakdown is apparent for the first time here because of the extraordinarily large Delta E-Z and small sigma achieved by nanocrystal diffusion doping.

• 出版日期2015-8-6