TiN/AlN Multilayered Metamaterial Superconductors

We have studied the effects of metamaterial engineering on TiN/AlN multilayered structures with ultrathin layers. It is known that decreasing the thickness of a superconducting thin film will reduce the critical temperature, Tc. Ultrathin TiN films are insulating for the film thickness of 4.5 nm and below. We have shown that creating TiN/AlN multilayers with hyperbolic properties increases the Tc compared with the single layer TiN of the same single layer thickness, and even restores the superconductivity for ultrathin layers in TiN/AlN multilayers. The anisotropy of the dielectric function and the resistivity of TiN/AlN multilayered samples were studied. The dependence of Tc and other parameters on the thickness of the AlN and TiN layers will be discussed.