1304.4516 (A. Romanenko et al.)

Dependence of the microwave surface resistance of superconducting
niobium on the magnitude of the rf field    [PDF]

A. Romanenko, A. Grassellino

Utilizing difference in temperature dependencies we decoupled BCS and residual components of the microwave surface resistance of superconducting niobium at all rf fields up to $B_\mathrm{rf}\sim110$ mT. We reveal that the residual resistance decreases with field at $B_\mathrm{rf} \lesssim$ 40 mT and strongly increases in chemically treated niobium at $B_\mathrm{rf} > 80$ mT. We find that BCS surface resistance is weakly dependent on field in the clean limit, whereas a strong and peculiar field dependence emerges after $120^\circ$C vacuum baking.

View original: http://arxiv.org/abs/1304.4516