Synthesis and applications of magnetic van der Waals material: Transition metal phosphorus tri-chalcogenides

Abstract

Among van der Waals materials which have a layered structure and a weak van der Waals interaction between the layers, the magnetic transition metal phosphorus tri-chalcogenides (TMPX3) were studied. Especially, the exfoliated flakes of TMPX3 were obtained by mechanical exfoliation on various substrates and studied as a form of tunnel junction using the vertical transport measurement.

I studied tunneling transport properties of several exfoliated MnPS3 flakes with thickness varying from monolayer to a few tens of layers. To measure current through the ultrathin nanostructures, conductive atomic force microscopy was the instrument of choice. Using the results, I estimated several key parameters of MnPS3 down to the monolayer such as tunneling barrier height and dielectric breakdown strength.

In addition, the first vdW heterostructure with few-layers of NiPS3 was realized by dry transfer technique using the new polymer called polycaprolactone. I performed vertical transport measurements in this system and successfully observed semiconducting behavior with the key features of a Schottky junction. I expect that these results will prove helpful for further research on magnetism and spintronics in vdW systems.