Exploring Substitution Doping of Fe in WTe₂Using Scanning Tunneling Microscopy and Spectroscopy (STM/S)

Transition Metal Dichalcogenides (TMDs) have been shown to intrinsically possess wide range of material properties from metallic to insulating and a variety of topological phenomena. Hence, TMD materials are of importance in electronics and photonics. In general, TMDs in their intrinsic state are nonmagnetic. The magnetism is expected to be introduced by doping with magnetic elements.

Here, we present preliminary results from scanning tunneling microscopy and spectroscopy (STM/S) on Fe doped WTe₂ (Fe_xW_1-xTe₂, x = 2.6%). At this doping level, Fe is revealed to be at substitution rather than intercalation sites through experimental STM/S study and by the density functional theory (DFT) calculations. The total doping concentration observed with STM/S agrees with the results obtained from the energy dispersive X-ray spectroscopy (EDS). Furthermore, STM/S data shows that the Fe substitution are equally probable at the two possible W sites in the unit cell. The Fe dopants provide electron doping as determined by Hall measurements as well as dI/dV spectra in STM/S measurements.