Spin-Related Optical Behaviors of Diluted Magnetic Semiconductor ZnSe:Ni(II) Nanobelts

There are varied spin states in diluted magnetic semiconductor, carrier is not the only elementary excitation carrying the spin freedom. This article reports the study of spin interactions in excitons of ZnSe:NiI(II) nanostructures. High quality ZnSe:NiI(II) nanobelts(NBs) prepared by chemical vapor deposition(CVD) technique show sphalerite structure by X-ray diffraction and Raman spectra, the latter show clear structural instability. The temperature-dependent photoluminescence spectra of highly doped NB shows independent Free exciton(FX) and exciton magnetic polarons (EMP) peaks at room temperature, with the ferromagentic(FM) coupled Ni ions. A single mode lasing profile was obtained by the femtosecond laser excitation due to the EMP condensation over a threshold. The luminescence lifetimes at different pump powers indicated the emission of coherent EMP aggregates. A weak side-peak at high energy side of FX could show up separately at low temperature, that should be the magnetic polaron emission band out of the antiferromagnetic (AFM) coupled Ni(II) pair binding with FX (AMP). Both bands out of AFM and FM could be identified in their d-d transition of Ni ions, combination with clearly relaxed structures. These results illustrate the typical spectroscopic characteristics of spin-spin magnetic coupling, exciton-spin or phonon interactions in DMS nanostructures, reflecting their different coupled spin type could work as exciton binder for their collective excitons , possibly used for spin nanophotonic devices and quantum modulations.