Title:

Characterizing Insulating States in TaS2 with Atomic Adsorbates

When tantalum disulfide (TaS2) is cooled, it goes through a series of phase transitions, eventually entering an insulating state. The type of insulating state - conventional band insulator or Mott insulator - is debated among researchers. Based on the electronic response of the material to atomic adsorbates (adatoms), we can experimentally make this determination. In this experiment, I deposited gold atoms on a TaS2 sample and studied the surface with scanning tunneling microscopy (STM) and spectroscopy. I present evidence of gold doping the sample, as indicated by a band gap shift while gap size is unchanged. This electronic response corresponds to a conventional band insulator. Literature suggest that stacking order of crystal layers determines the type of insulating state. I propose a straightforward experimental way to test this hypothesis. Future work will include exploration of the stacking order dependence and a search for Mott insulating surfaces.

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