Exploring magneto-optic properties of colloidal two-dimensional copper-doped CdSe nanoplatelets

Transition-metal-doped semiconductor nanocrystals have received significant attention because of their attractive features deeming them invaluable in various technological fields including optoelectronics, biophotonics, and energy conversion, to name a few. Of particular, these interests are two-dimensional materials with useful optical and magnetic properties combined with their large surface areas opening up new applications in biotechnology. These applications range from multimodal optical and magnetic bioimaging and sensing to measuring the weak magnetic field due to brain waves using their magneto-optic properties stemming from the exchange interaction between the transition metal dopants and the carrier spins. These magnetic 2D materials could also significantly advance the field of spintronics. In this work, we report on a study of the magnetic and magneto-optic properties of colloidal two-dimensional (2D) copper-doped CdSe nanoplatelets (NPLs) that are synthesized using a high-temperature colloidal technique. We carried out optical and circularly polarized magneto-photoluminescence spectrometry to investigate the magnetism in our solution-processed nanostructures doped with copper ion impurities. At cryogenic temperatures, two excitonic features are observed for doped NPLs, which are more prominent compared to the undoped NPLs. Furthermore, the excitonic circular polarization (CP) is recorded as a function of the applied magnetic field (B) and temperature (T). The detailed analysis provides a picture of the magneto-optical behavior of the doped 2D NPLs in the presence of paramagnetic copper ions. This work paves the way for significant advances in bio/nanophotonics where tunable optical and magnetic properties of doped nanoplatelets can be leveraged to make more efficient, flexible, and low-cost devices.