Effect of metamaterial engineering on the superconductive properties of ultrathin layers of NbTiN

Abstract

The electronic transport and optical properties of high quality multilayers of NbTiN/AlN with ultrathin NbTiN layers were characterized. The anisotropy of the dielectric function of the multilayers confirmed their hyperbolic metamaterial properties. The superconductive transition temperature, T c , of these engineered superconductors was enhanced up to 32% compared to the T c of a single ultrathin NbTiN layer while the resistivity per NbTiN layer remained unchanged. We have demonstrated that this T c increase can be attributed to enhanced electron-electron interaction in superconducting hyperbolic metamaterials. The measured critical fields are high and have an anomalous temperature dependence on the direction perpendicular to the magnetic field. These results demonstrate that the metamaterial engineering approach can be used to enhance H c2 .

Successful Al2O3 coating of superconducting niobium cavities with thermal ALD

“…Experimental studies on samples, proving the field enhancement properties of SIS layers, and studies on deposition parameters correlating with material properties have been carried out [17][18][19][20][21][22][23]. While these studies were performed applying sputtering techniques to deposit the SIS films on flat samples, Proslier et al and Eremeev et al used thermal atomic layer deposition (ALD) to study the impact of an insulating Al 2 O 3 layer on cavities [24][25][26][27].…”