Scanning tunneling measurements of layers of superconducting 2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>H</mml:mi></mml:math>-TaSe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>: Evidence for a zero-bias anomaly in single layers

We report a characterization of surfaces of the dichalcogenide TaSe${}_{2}$ using scanning tunneling microscopy and spectroscopy at 150 mK. When the top layer has the $2H$ structure and the layer immediately below the $1T$ structure, we find a singular spatial dependence of the tunneling conductance below 1 K, changing from a zero-bias peak on top of Se atoms to a gap in between Se atoms. The zero-bias peak is additionally modulated by the commensurate $3{a}_{0}\ifmmode\times\else\texttimes\fi{}3{a}_{0}$ charge-density wave of $2H$-TaSe${}_{2}$. Multilayers of $2H$-TaSe${}_{2}$ show a spatially homogeneous superconducting gap with a critical temperature also of 1 K. We discuss possible origins for the peculiar tunneling conductance in single layers.