Superconductivity dependent friction of water, nitrogen, and superheated he films adsorbed on Pb(111)

We report a quartz crystal microbalance study of sliding friction levels in N-2, H2O, and superheated He films adsorbed on Pb(111) substrates alternating in and out of the superconducting state. Reductions in friction upon entry into the superconducting state are greater for N-2 than He, consistent with a recent theory that linked electronic friction to adsorbate polarizability. Our work also reveals that repetitive cycling of an externally applied magnetic field may impact friction.