Superconducting Scanning Tunneling Microscope Tip to Reveal Sub-millielectronvolt Magnetic Energy Variations on Surfaces

We show extraordinary energy resolution with an STM by using a superconducting tip with sharp quasiparticle density of states. This permits us to reveal small changes in molecular magnetic anisotropy energy depending on the adsorption site and orientation. As a consequence, we show that a two-dimensional array of nickelocene molecules on a Pb(111) substrate is highly non-collinear. 

 

The Journal of Physical Chemistry Letters 12, 2983–2989 (2021).