In 2006 Gurevich proposed to use nanoscale layers of superconducting materials with high
values of Hc> Hc^ Nb for magnetic shielding of bulk niobium to increase the breakdown
magnetic field inside SC RF cavities [1]. We have deposited high quality" model" samples by
magnetron sputtering on monocrystalline sapphire substrates. A 250 nm layer of niobium
figures the bulk Nb. It was coated with a single and multi-stacks of NbN layers (25 or12 nm)
separated by 15 nm MgO barriers, and characterized by X-Ray reflectivity and DC transport …

In 2006 Gurevich proposed to use nanoscale layers of superconducting materials with high
values of Hc> Hc Nb for magnetic shielding of bulk niobium to increase the breakdown
magnetic field inside SC RF cavities [1]. We have deposited high quality “model” samples by
magnetron sputtering on monocrystalline sapphire substrates. A 250 nm layer of niobium
figures the bulk Nb. It was coated with a single and multi-stacks of NbN layers (25 or12 nm)
separated by 15 nm MgO barriers, and characterized by X-Ray reflectivity and DC transport …