Intrinsic Long-Range Magnetism in Semiconducting Transition Metal Dichalcogenides
The search has been ongoing for several decades for dilute magnetic semiconductors, materials with a semiconducting bandgap and long range magnetic interaction, the combination of which makes them ideal for spintronic applications. The transition metal dichalcogenides have also been of great interest in recent years as they can be isolated to monolayers, like graphene, and have an intrinsic direct bandgap in the optical wavelength making them great 2D semiconductors for electronic and optical applications. To date, however, magnetism in the semiconducting transition metal dichalcogenides is not well studied as the pristine lattices are not predicted to exhibit magnetism. In this talk, we report the direct experimental observation of magnetism below TM=40K and TM=100K in bulk 2H-MoTe2 and 2H-MoSe2 respectively by muon spin relaxation/rotation (µSR), as well as a weaker magnetic order onsetting at higher temperatures. From atomic-resolution scanning tunneling microscopy (STM), we show that as-grown transition metal dichalcogenide bulk crystals have naturally occurring, uniform distributions of a multitude of defects native to the transition metal dichalcogenide lattices. For one such defect, a transition metal substitution for a chalcogen, Hubbard-Corrected Density Functional Theory predicts an induced magnetic moment at defect sites with long range interaction, thus making it the likely cause of the unexpected magnetism. Our most recent unpublished STM results further confirm this defect as the source of the magnetism.
Pizza lunch: 12pm - 12:30pm
Seminar: 12:30pm - 1:30pm