Superinsulator

A superinsulator is a material that at low but finite temperatures does not conduct electricity, i.e. has an infinite resistance so that no electric current passes through it. The phenomenon of superinsulation can be regarded as an exact dual to superconductivity.

The superinsulating state can be destroyed by increasing the temperature and applying an external magnetic field and voltage. A superinsulator was first predicted by M. C. Diamantini, P. Sodano, and C. A. Trugenberger in 1996 who found a superinsulating ground state dual to superconductivity, emerging at the insulating side of the superconductor-insulator transition in the Josephson junction array due to electric-magnetic duality. Superinsulators were independently rediscovered by T. Baturina and V. Vinokur in 2008 on the basis of duality between two different symmetry realizations of the uncertainty principle and experimentally found in titanium nitride (TiN) films. The 2008 measurements revealed giant resistance jumps interpreted as manifestations of the voltage threshold transition to a superinsulating state which was identified as the low-temperature confined phase emerging below the charge Berezinskii-Kosterlitz-Thouless transition. These jumps were similar to earlier findings of the resistance jumps in indium oxide (InO) films. The finite-temperature phase transition into the superinsulating state was finally confirmed by Mironov et al. in NbTiN films in 2018.

Other researchers have seen the similar phenomenon in disordered indium oxide films.