Magnetic Defects in Transitional Metal Di-Chalcogenide Semiconducting Layers

In this work, we report on the electron spin resonance (ESR) studies performed on few-layered nanocrystalline (NCs) MoS 2 , WS 2 , and TiS 2 prepared using hydrothermal and vapor transport methods. From the temperature dependent ESR spectra collected from MoS 2 NCs, we have identified adsorbed oxygen species, sulphur vacancies, thio- and oxo-Mo 5+ related paramagnetic defect centers. WS 2 NCs have exhibited W +3 and oxo-W +5 paramagnetic defect spin species. TiS 2 NCs showed defects such as Fe 3+ (unwanted), oxygen and sulfur vacancies. This work demonstrates the usage of spin-sensitive spectroscopy such as ESR in unravelling the defects which contain unpaired electron spin centers in layered NCs two-dimensional materials.