We describe a study of the magneto-optical properties of Ag + -doped CdSe colloidal nanoplatelets (NPLs) that were grown using a novel doping technique. In this work, we used magnetic circularly polarized luminescence and magnetic circular dichroism spectroscopy to study light-induced magnetism for the first time in 2D solution-processed structures doped with nominally nonmagnetic Ag + impurities. The excitonic circular polarization (P X ) and the exciton Zeeman splitting (ΔE Z ) were recorded as a function of the magnetic field (B) and temperature (T). Both ΔE Z and P X have a Brillouin-function-like dependence on B and T, verifying the presence of paramagnetism in Ag + -doped CdSe NPLs. The observed light-induced magnetism is attributed to the transformation of nonmagnetic Ag + ions into Ag 2+ , which have a nonzero magnetic moment. This work points to the possibility of incorporating these nanoplatelets into spintronic devices, in which light can be used to control the spin injection.

We utilized time-resolved photoluminescence (TRPL) spectroscopy to study the excitonic circular polarization (P X ) from CdSe/CdMnS core/shell nanoplatelets (NPLs) with a bilayer core. This allows an extensive study of the emission dynamics as a function of magnetic field, temperature, doping concentration, and excitation wavelength. In the presence of an external magnetic field, pulsed excitation below the shell gap results in near-zero excitonic circular polarization P X at all time delays. In contrast, pulsed excitation with photon energy larger than the shell gap results in a rapid (100 ps) buildup of the excitonic circular polarization which subsequently remains constant at a level of up to 40%. We propose a model to describe the dynamics which takes into account the exchange interaction between carrier and magnetic ion (Mn) spins. The studied system exhibits a fast switchable excitonic circular polarization, implying possible applications in lasers and light emitting diodes.

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In this article, we present a comprehensive study of temperature and composition dependent Raman spectroscopy of Ge x As 35-x Se 65 thin films to understand different structural units responsible for optical properties. Strikingly, our experimental results uncover the ratio of GeSe 4/2 tetrahedral and AsSe 3/2 pyramidal units in Ge x As 35-x Se 65 thin films and their linear scaling relationship with temperature and x. An important notable outcome of our study is the formation of Se 8 rings at lower temperatures. Our experimental results further provide interesting optical features-thermally and compositionally tunable optical absorption spectra. Detailed structure specific FIR data at room temperature also present direct information on the structural units in consistent with Raman data. We foresee that our studies are useful in determining the lightinduced response of these films and also for their potential applications in optics and optoelectronics.

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