Defect mediated magnetic transitions in Fe and Mn doped MoS2.

Abstract

We report single-phase syntheses of undoped 2H-MoS2 as well as Mn and Fe doped MoS2 by a facile hydrothermal route. The formation of the 2H-MoS2 phase was confirmed by XRD and was corroborated with Raman spectra. The morphology of the doped and undoped MoS2 nanostructures comprised sheets, as revealed by TEM and STEM images. The fine granular structure was observed by high resolution TEM micrographs. The STEM-EDS results show dopant concentrations of ∼1 atom% corresponding to Mn and Fe in doped MoS2. The undoped MoS2 revealed diamagnetic behavior at room temperature and paramagnetic behavior in the range (100 to 300 K). The Mn-MoS2 sample displayed ferromagnetism below 20 K with a coercive field of ∼50 Oe. Such a sample may be utilized for magnetic switching purposes at low temperatures. The onset of the antiferromagnetic interaction was observed below 145 K in Fe-MoS2 samples. They have been understood in terms of long-range magnetic interactions amongst the dipole moments mediated via surface defects as well as the interaction between the dipoles and the surface charges. The findings are corroborated with the help of EPR studies.