Physicists discover the 'superinsulator'

An international team of researchers has discovered what it describes as the reverse side of a superconductor — a “superinsulator” that indefinitely retains electrical charge.

Christoph Strunk of Regensburg University in Germany, whose team includes Valerii Vinokur of Argonne National Laboratory in the US and other colleagues from Germany, the US and Belgium, found the state in thin films of titanium nitride cooled towards absolute zero in a magnetic field. Although the material is usually a superconductor, in which electrical current can propagate without resistance, the team have found that in these conditions the material’s resistance rises to infinity (Nature 452 613).

“In the 1990s it became apparent in a number of measurements that a quantum phase transition — that is, a transition between two ordered states at zero Kelvin — is a great place to look for new kinds of ordered states,” says Stephen Julian, a low-temperature physicist at the University of Toronto, Canada. “This [research] seems to be quite an unexpected and beautiful example of this: a superinsulator on the boundary between the ordinary insulator and the superconducting ground state.”