Abstract
The search for electrolyte materials with high oxygen conductivities is a key step towards reducing the operation temperature of fuel cells for room temperature applications. Here, we report an extraordinarily high lateral ionic conductivity, up to 8 orders of magnitude enhancement near room temperature, in yttria stabilized zirconia (YSZ) / SrTiO3 (STO) epitaxial heterostructures. This huge enhancement of the conductivity is observed independently of YSZ layer thickness, showing it is a genuine interface process. We propose that the atomic reconstruction at the highly coherent interface between such dissimilar structures (fluorite and perovskite) provides both a large number of carriers and a high mobility plane, yielding colossal values of the ionic conductivity.