Single and double electron spin-flip Raman scattering in CdSe colloidal nanoplatelets

TL;DR

This study investigates spin-flip Raman scattering in CdSe colloidal nanoplatelets, revealing single and double electron spin-flip processes influenced by magnetic fields and exciton-electron interactions.

Contribution

It provides the first detailed analysis of double electron spin-flip Raman scattering in colloidal nanoplatelets, combining experimental observations with theoretical insights.

Findings

Observation of Raman lines shifted by electron Zeeman splitting

Detection of Raman signals shifted by twice the electron Zeeman splitting

Analysis of exciton-resident electron interactions affecting scattering

Abstract

CdSe colloidal nanoplatelets are studied by spin-flip Raman scattering in magnetic fields up to 5 T. We find pronounced Raman lines shifted from the excitation laser energy by an electron Zeeman splitting. Their polarization selection rules correspond to those expected for scattering mediated by excitons interacting with resident electrons. Surprisingly, Raman signals shifted by twice the electron Zeeman splitting are also observed. The theoretical analysis and experimental dependencies show that the mechanism responsible for the double flip involves two resident electrons interacting with a photoexcited exciton. Effects related to various orientations of the nanoplatelets in the ensemble and different orientations of the magnetic field are analyzed.