MAGNETO-OPTICAL SPECTROSCOPY OF NANOCRYSTALS AND NANOPLATELETS
Colloidal nanocrystal (quantum dots and nanoplatelets) are nanometer-sized, single-crystal metals or semiconductors that are strongly coupled to optical excitation. Research into the optical properties of quantum dots over the past two decades has focused on diameter-controlled band gap energies, increased photon-to-carrier extraction efficiencies, single-photon emission, and quantum dot lasing. In the Rice lab, we are interested in studying magnetically doped, semiconducting nanocrystals to examine how optically generated excitons affect and are affecting by magnetic dopants. Our recent work on exciton magnetic polarons suggests that the interplay between excitons and magnetic dopants is a rich arena for interesting physics.
Figure 1: Colloidal ZnCdSeS NCs produced by PlasmaChem showing bandgap tunability from violet to red (
Figure 2: Exciton magnetic polarons can readily form in magnetic quantum dots when an exciton is created. Our recent work (Nano Letters, doi: 10.1021/acs.nanolett.7b00421) shows that spontaneous alignment of the magnetic dopants occurs because exciton exerts a ~10 T field upon the magnetic ions.
We are also currently working with novel nanoplatelet (NPL) materials. Ag2S NPLs (produced in the Parkinson lab by Lenore Kubie) show interesting optical properties in the near infrared. Given recently collected data (see our new ACS Nano paper), we are excited to see what new surprises are in store with this material.