Speaker
Description
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, Tc, of these engineered superconductors was enhanced up to 32% compared to the Tc of a single ultrathin NbTiN layer while the resistivity per NbTiN layer remained unchanged. We have demonstrated that this Tc 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 Hc2.
This work was supported in part by DARPA under Award No. W911NF-17-1-0348 “Metamaterial Superconductors”; by ONR under Award Nos. N0001418-1-2681, N0001418WX00078, and N00014-18- 1-2653; and by ONR under the Naval Research Laboratory base program. A.-M. Valente-Feliciano and D.R. Beverstock are also supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contract No. DE-AC05-06OR23177.
