A new quasi-2D superconductor that bridges a ferroelectric and an insulator

Researchers at the Zavoisky Physical-Technical Institute and the Southern Scientific Center of RAS, in Russia, have recently fabricated quasi-2-D superconductors at the interface between a ferroelectric Ba_0.8Sr_0.2TiO₃ film and an insulating parent compound of La₂CuO₄. Their study, presented in a paper published in Physical Review Letters, is the first to achieve superconductivity in a heterostructure consisting of a ferroelectric and an insulator.

The idea of forming a quasi-2-D superconducting layer at the interface between two different compounds has been around for several years. One past study, for instance, tried to achieve this by creating a thin superconducting layer between two insulating oxides (LaAlO₃ and SrTiO₃) with a critical temperature of 300mK. Other researchers observed the thin superconducting layer in bilayers of an insulator (La₂CuO₄) and a metal (La_1.55Sr_0.45CuO₄), neither of which is superconducting in isolation.

"Here we put forward the idea that thin charged layer on the interface between ferroelectric and insulator is formed in order to screen the electric field," Viktor Kabanov and Rinat Mamin, two researchers who carried out the study, told Phys.org via email. "This thin layer may be conducting or superconducting depending on the properties of the insulator. In order to get a superconducting layer, we chose La₂CuO₄ – an insulator that becomes a high T_c superconductor when it is doped by carriers."